webrtc: use correct cwd for running tests

scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_linux_memcheck.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "\nimport sys, os\npath = sys.argv[1]\nmode = int(sys.argv[2])\nif not os.path.isdir(path):\n  if os.path.exists(path):\n    print \"%s exists but is not a dir\" % path\n    sys.exit(1)\n  os.makedirs(path, mode)\n",
       "[BUILDER_CACHE]/linux_memcheck",
       "511"
     ],
     "name": "makedirs checkout path",
@@ skipping 250 matching lines @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--pass-build-dir",
       "--pass-target",
       "--run-shell-script",
       "[BUILDER_CACHE]/linux_memcheck/src/tools/valgrind-webrtc/webrtc_tests.sh",
       "--test",
       "audio_decoder_unittests",
       "--tool",
       "memcheck"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_memcheck",
     "name": "audio_decoder_unittests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
@@ skipping 11 matching lines @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--pass-build-dir",
       "--pass-target",
       "--run-shell-script",
       "[BUILDER_CACHE]/linux_memcheck/src/tools/valgrind-webrtc/webrtc_tests.sh",
       "--test",
       "common_audio_unittests",
       "--tool",
       "memcheck"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_memcheck",
     "name": "common_audio_unittests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
@@ skipping 11 matching lines @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--pass-build-dir",
       "--pass-target",
       "--run-shell-script",
       "[BUILDER_CACHE]/linux_memcheck/src/tools/valgrind-webrtc/webrtc_tests.sh",
       "--test",
       "common_video_unittests",
       "--tool",
       "memcheck"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_memcheck",
     "name": "common_video_unittests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
@@ skipping 11 matching lines @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--pass-build-dir",
       "--pass-target",
       "--run-shell-script",
       "[BUILDER_CACHE]/linux_memcheck/src/tools/valgrind-webrtc/webrtc_tests.sh",
       "--test",
       "modules_tests",
       "--tool",
       "memcheck"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_memcheck",
     "name": "modules_tests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
@@ skipping 11 matching lines @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--pass-build-dir",
       "--pass-target",
       "--run-shell-script",
       "[BUILDER_CACHE]/linux_memcheck/src/tools/valgrind-webrtc/webrtc_tests.sh",
       "--test",
       "modules_unittests",
       "--tool",
       "memcheck"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_memcheck",
     "name": "modules_unittests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
@@ skipping 11 matching lines @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--pass-build-dir",
       "--pass-target",
       "--run-shell-script",
       "[BUILDER_CACHE]/linux_memcheck/src/tools/valgrind-webrtc/webrtc_tests.sh",
       "--test",
       "peerconnection_unittests",
       "--tool",
       "memcheck"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_memcheck",
     "name": "peerconnection_unittests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
@@ skipping 11 matching lines @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--pass-build-dir",
       "--pass-target",
       "--run-shell-script",
       "[BUILDER_CACHE]/linux_memcheck/src/tools/valgrind-webrtc/webrtc_tests.sh",
       "--test",
       "rtc_media_unittests",
       "--tool",
       "memcheck"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_memcheck",
     "name": "rtc_media_unittests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
@@ skipping 11 matching lines @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--pass-build-dir",
       "--pass-target",
       "--run-shell-script",
       "[BUILDER_CACHE]/linux_memcheck/src/tools/valgrind-webrtc/webrtc_tests.sh",
       "--test",
       "rtc_pc_unittests",
       "--tool",
       "memcheck"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_memcheck",
     "name": "rtc_pc_unittests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
@@ skipping 11 matching lines @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--pass-build-dir",
       "--pass-target",
       "--run-shell-script",
       "[BUILDER_CACHE]/linux_memcheck/src/tools/valgrind-webrtc/webrtc_tests.sh",
       "--test",
       "rtc_unittests",
       "--tool",
       "memcheck"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_memcheck",
     "name": "rtc_unittests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
@@ skipping 11 matching lines @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--pass-build-dir",
       "--pass-target",
       "--run-shell-script",
       "[BUILDER_CACHE]/linux_memcheck/src/tools/valgrind-webrtc/webrtc_tests.sh",
       "--test",
       "system_wrappers_unittests",
       "--tool",
       "memcheck"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_memcheck",
     "name": "system_wrappers_unittests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
@@ skipping 11 matching lines @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--pass-build-dir",
       "--pass-target",
       "--run-shell-script",
       "[BUILDER_CACHE]/linux_memcheck/src/tools/valgrind-webrtc/webrtc_tests.sh",
       "--test",
       "test_support_unittests",
       "--tool",
       "memcheck"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_memcheck",
     "name": "test_support_unittests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
@@ skipping 11 matching lines @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--pass-build-dir",
       "--pass-target",
       "--run-shell-script",
       "[BUILDER_CACHE]/linux_memcheck/src/tools/valgrind-webrtc/webrtc_tests.sh",
       "--test",
       "tools_unittests",
       "--tool",
       "memcheck"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_memcheck",
     "name": "tools_unittests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
@@ skipping 11 matching lines @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--pass-build-dir",
       "--pass-target",
       "--run-shell-script",
       "[BUILDER_CACHE]/linux_memcheck/src/tools/valgrind-webrtc/webrtc_tests.sh",
       "--test",
       "video_engine_tests",
       "--tool",
       "memcheck"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_memcheck",
     "name": "video_engine_tests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
@@ skipping 11 matching lines @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--pass-build-dir",
       "--pass-target",
       "--run-shell-script",
       "[BUILDER_CACHE]/linux_memcheck/src/tools/valgrind-webrtc/webrtc_tests.sh",
       "--test",
       "voice_engine_unittests",
       "--tool",
       "memcheck"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_memcheck",
     "name": "voice_engine_unittests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
@@ skipping 11 matching lines @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--pass-build-dir",
       "--pass-target",
       "--run-shell-script",
       "[BUILDER_CACHE]/linux_memcheck/src/tools/valgrind-webrtc/webrtc_tests.sh",
       "--test",
       "xmllite_xmpp_unittests",
       "--tool",
       "memcheck"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_memcheck",
     "name": "xmllite_xmpp_unittests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
@@ skipping 11 matching lines @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--pass-build-dir",
       "--pass-target",
       "--run-shell-script",
       "[BUILDER_CACHE]/linux_memcheck/src/tools/valgrind-webrtc/webrtc_tests.sh",
       "--test",
       "webrtc_nonparallel_tests",
       "--tool",
       "memcheck"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_memcheck",
     "name": "webrtc_nonparallel_tests"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]