Recipes: make cwd default to slave_build

scripts/slave/recipes/chromium_gn.expected/compile_failure.json

Index: scripts/slave/recipes/chromium_gn.expected/compile_failure.json
diff --git a/scripts/slave/recipes/chromium_gn.expected/compile_failure.json b/scripts/slave/recipes/chromium_gn.expected/compile_failure.json
index e968409fe3f4c01ac788348863967272a77d762a..b8c504c63fd144011c9b11d18848d9aafecfd154 100644
--- a/scripts/slave/recipes/chromium_gn.expected/compile_failure.json
+++ b/scripts/slave/recipes/chromium_gn.expected/compile_failure.json
@@ -28,6 +28,7 @@
       "src@HEAD",
       "--force"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "bot_update",
     "~followup_annotations": [
       "@@@STEP_TEXT@Some step text@@@",
@@ -74,6 +75,7 @@
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "GYP_CHROMIUM_NO_ACTION": "1"
     },
@@ -96,6 +98,7 @@
       "[BUILD]/goma",
       "//out/Release"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "Generate build files"
   },
   {
@@ -106,6 +109,7 @@
       "[SLAVE_BUILD]/src/testing/buildbot/tryserver.chromium.linux.json",
       "/path/to/tmp/json"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "read test spec",
     "~followup_annotations": [
       "@@@STEP_TEXT@path: [SLAVE_BUILD]/src/testing/buildbot/tryserver.chromium.linux.json@@@",
@@ -142,6 +146,7 @@
       "[SLAVE_BUILD]/src/testing/buildbot/trybot_analyze_config.json",
       "/path/to/tmp/json"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "read filter exclusion spec",
     "~followup_annotations": [
       "@@@STEP_TEXT@path: 'testing/buildbot/trybot_analyze_config.json'@@@",
@@ -174,6 +179,7 @@
       "{\"files\": [\"foo.cc\"], \"targets\": [\"base_unittests\", \"all\"]}",
       "/path/to/tmp/json"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "analyze",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
@@ -225,6 +231,7 @@
       "--",
       "base_unittests"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "compile",
     "~followup_annotations": [
       "step returned non-zero exit code: 1",