Recipes: make cwd default to slave_build

scripts/slave/recipes/nacl/sdk_build.expected/basic.json

Index: scripts/slave/recipes/nacl/sdk_build.expected/basic.json
diff --git a/scripts/slave/recipes/nacl/sdk_build.expected/basic.json b/scripts/slave/recipes/nacl/sdk_build.expected/basic.json
index 4462a240f64482f7fea067b8b99eb60b70d4dd30..ad42f1aa86ae8f4387b197b109add10b79362304 100644
--- a/scripts/slave/recipes/nacl/sdk_build.expected/basic.json
+++ b/scripts/slave/recipes/nacl/sdk_build.expected/basic.json
@@ -22,6 +22,7 @@
       "src@HEAD",
       "--force"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "bot_update",
     "~followup_annotations": [
       "@@@STEP_TEXT@Some step text@@@",
@@ -68,6 +69,7 @@
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "GYP_DEFINES": "component=static_library gomadir='[BUILD]/goma' target_arch=x64 use_goma=1"
     },
@@ -79,6 +81,7 @@
       "-u",
       "[BUILD]/scripts/slave/cleanup_temp.py"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "cleanup_temp"
   },
   {
@@ -88,6 +91,7 @@
       "-u",
       "[SLAVE_BUILD]/src/native_client_sdk/src/build_tools/buildbot_run.py"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "annotated_steps"
   }
 ]