Recipes: make cwd default to slave_build

scripts/slave/recipes/v8.expected/full_client_v8_V8_Linux___arm___sim.json

Index: scripts/slave/recipes/v8.expected/full_client_v8_V8_Linux___arm___sim.json
diff --git a/scripts/slave/recipes/v8.expected/full_client_v8_V8_Linux___arm___sim.json b/scripts/slave/recipes/v8.expected/full_client_v8_V8_Linux___arm___sim.json
index 352d5b8828ff05ffdced469666c63feed8dcacff..223c26accbe1134d601d0fb337911bf07cafec7b 100644
--- a/scripts/slave/recipes/v8.expected/full_client_v8_V8_Linux___arm___sim.json
+++ b/scripts/slave/recipes/v8.expected/full_client_v8_V8_Linux___arm___sim.json
@@ -23,6 +23,7 @@
       "--no_shallow",
       "--output_manifest"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "bot_update",
     "~followup_annotations": [
       "@@@STEP_TEXT@Some step text@@@",
@@ -55,6 +56,7 @@
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "GYP_DEFINES": "gomadir='[BUILD]/goma' target_arch=ia32 use_goma=1 v8_target_arch=arm"
     },
@@ -66,6 +68,7 @@
       "-u",
       "[BUILD]/scripts/slave/cleanup_temp.py"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "cleanup_temp"
   },
   {
@@ -85,6 +88,7 @@
       "[BUILD]/goma",
       "--"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "compile"
   },
   {