Add counting the number of CPU's in goma module

scripts/slave/recipes/chromium.chromedriver.recipe_autogen.expected/Win7.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/kill_processes.py"
     ],
     "name": "taskkill"
   },
   {
@@ skipping 155 matching lines @@
       "@@@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": [
+      "python",
+      "-u",
       "[SLAVE_BUILD]/src/tools/mb/mb.py",
       "gen",
       "-m",
       "chromium.chromedriver",
       "-b",
       "Win7",
       "--goma-dir",
       "[CACHE]/cipd/goma",
       "//out/Default"
     ],
@@ skipping 26 matching lines @@
       "--factory-properties={\"annotated_script\":\"chromedriver_buildbot_run.py\",\"blink_config\":\"chromium\",\"gclient_env\":{\"DEPOT_TOOLS_UPDATE\":\"0\",\"LANDMINES_VERBOSE\":\"1\"},\"needs_webdriver_java_tests\":true}"
     ],
     "name": "annotated_steps"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]