Recipes: make cwd default to slave_build

scripts/slave/recipes/chromium_trybot.expected/runhooks_failure.json

Index: scripts/slave/recipes/chromium_trybot.expected/runhooks_failure.json
diff --git a/scripts/slave/recipes/chromium_trybot.expected/runhooks_failure.json b/scripts/slave/recipes/chromium_trybot.expected/runhooks_failure.json
index fe6cc1cc48d7a4313ecf63b3937079058cadd05a..75248b1108974964698f5b517f52b69b9846d1cd 100644
--- a/scripts/slave/recipes/chromium_trybot.expected/runhooks_failure.json
+++ b/scripts/slave/recipes/chromium_trybot.expected/runhooks_failure.json
@@ -5,6 +5,7 @@
       "-u",
       "[BUILD]\\scripts\\slave\\kill_processes.py"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "taskkill"
   },
   {
@@ -35,6 +36,7 @@
       "--revision",
       "src@HEAD"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "bot_update",
     "~followup_annotations": [
       "@@@STEP_TEXT@Some step text@@@",
@@ -81,6 +83,7 @@
       "[SLAVE_BUILD]\\src\\tools\\swarming_client\\swarming.py",
       "--version"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "swarming.py --version",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
@@ -94,6 +97,7 @@
       "[DEPOT_TOOLS]\\gclient.py",
       "runhooks"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "GYP_DEFINES": "archive_gpu_tests=1 chromium_win_pch=0 component=static_library dcheck_always_on=1 fastbuild=1 gomadir='[BUILD]\\goma' target_arch=ia32 test_isolation_mode=prepare use_goma=1"
     },
@@ -109,6 +113,7 @@
       "-u",
       "[BUILD]\\scripts\\slave\\kill_processes.py"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "taskkill (2)"
   },
   {
@@ -136,6 +141,7 @@
       "src@f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--force"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "bot_update (without patch)",
     "~followup_annotations": [
       "@@@STEP_TEXT@Some step text@@@",
@@ -170,6 +176,7 @@
       "[DEPOT_TOOLS]\\gclient.py",
       "runhooks"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "GYP_DEFINES": "archive_gpu_tests=1 chromium_win_pch=0 component=static_library dcheck_always_on=1 fastbuild=1 gomadir='[BUILD]\\goma' target_arch=ia32 test_isolation_mode=prepare use_goma=1"
     },