Make gyp target_arch setting native to chromium/config.py

scripts/slave/recipes/android/instrumentation_tests.expected/main_tests.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[DEPOT_TOOLS]/gclient.py",
       "config",
       "--spec",
       "cache_dir = None\nsolutions = [{'deps_file': '.DEPS.git', 'managed': True, 'name': 'src/repo', 'url': 'svn://svn.chromium.org/chrome/trunk/src'}]\ntarget_os = ['android']"
     ],
@@ skipping 70 matching lines @@
       "@@@STEP_LOG_LINE@json.output@  \"SCREENSHOT_BUCKET\": \"screenshot-archive\"@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@"
     ]
   },
   {
     "cmd": [
       "[BUILD]/scripts/slave/env_dump.py",
       "--output-json",
       "/path/to/tmp/json",
-      "[SLAVE_BUILD]/src/build/android/envsetup.sh"
+      "[SLAVE_BUILD]/src/build/android/envsetup.sh",
+      "--target-arch=arm"
     ],
     "env": {
       "PATH": "[BUILD_INTERNAL]/scripts/slave/android:%(PATH)s"
     },
     "name": "envsetup",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"GYP_DEFINES\": \"my_new_gyp_def=aaa\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"GYP_SOMETHING\": \"gyp_something_value\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"PATH\": \"./\"@@@",
@@ skipping 221 matching lines @@
   {
     "always_run": true,
     "cmd": [
       "rm",
       "-rf",
       "[SLAVE_BUILD]/src/out/build_product_4f4b02f6b7fa20a3a25682c457bbc8ad589c8a00.zip"
     ],
     "name": "cleanup_build"
   }
 ]