Add counting the number of CPU's in goma module

scripts/slave/recipes/webrtc/ios.expected/trybot.json

 [
   {
     "cmd": [
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/ios/host_info.py",
       "--json-file",
       "/path/to/tmp/json"
     ],
     "name": "host and tools info",
     "~followup_annotations": [
       "@@@STEP_TEXT@<br />OS X 1.2.3, Xcode 6.7.8 (5D342509a)@@@",
@@ skipping 177 matching lines @@
       "@@@STEP_LOG_LINE@json.output@      \"instance_id\": \"resolved-instance_id-of-release---------\", @@@",
       "@@@STEP_LOG_LINE@json.output@      \"package\": \"infra_internal/goma/client/mac-amd64\"@@@",
       "@@@STEP_LOG_LINE@json.output@    }@@@",
       "@@@STEP_LOG_LINE@json.output@  ]@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@"
     ]
   },
   {
     "cmd": [
+      "python",
+      "-u",
+      "\nimport multiprocessing\nprint min(200, multiprocessing.cpu_count() * 10)\n"
+    ],
+    "name": "ensure_goma.get the number of cpus",
+    "stdout": "/path/to/tmp/",
+    "~followup_annotations": [
+      "@@@STEP_NEST_LEVEL@1@@@",
+      "@@@STEP_LOG_LINE@python.inline@@@@",
+      "@@@STEP_LOG_LINE@python.inline@import multiprocessing@@@",
+      "@@@STEP_LOG_LINE@python.inline@print min(200, multiprocessing.cpu_count() * 10)@@@",
+      "@@@STEP_LOG_END@python.inline@@@"
+    ]
+  },
+  {
+    "cmd": [
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/ios/find_xcode.py",
       "--json-file",
       "/path/to/tmp/json",
       "--version",
       "fake xcode version"
     ],
     "name": "find xcode",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{}@@@",
       "@@@STEP_LOG_END@json.output@@@"
@@ skipping 105 matching lines @@
       "@@@STEP_LOG_LINE@json.output (invalid)@null@@@",
       "@@@STEP_LOG_END@json.output (invalid)@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]