Add script tests for `gn check`, `gyp_flag_compare` to GN bot configs.

testing/buildbot/tryserver.chromium.linux.json

 {
   "android_chromium_gn_compile_dbg": {
     "additional_compile_targets": [
       "chrome_shell_apk",
       "mandoline:all"
     ],
     "gtest_tests": []
   },
   "android_chromium_gn_compile_rel": {
     "additional_compile_targets": [
       "chrome_shell_apk",
       "mandoline:all"
     ],
-    "gtest_tests": []
+    "gtest_tests": [],
+    "scripts": [

[Paweł Hajdan Jr., 2015/05/15 15:41:14]

Oops, note that chromium/chromium_trybot recipes which support scripts just
don't read this file. You'd need to find some other way to test this - likely to
use this from chromium/chromium_trybot recipes. I'd much rather not add new
functionality e.g. to chromium_trybot_legacy.

+      {
+        "name": "gn_check",
+        "script": "gn_check.py"
+      }
+    ]
   },
   "linux_chromium_gn_chromeos_dbg": {
     "additional_compile_targets": [
       "accessibility_unittests",
       "app_list_unittests",
       "aura_unittests",
       "browser_tests",
       "cacheinvalidation_unittests",
       "chromedriver_unittests",
       "chromeos_unittests",
@@ skipping 320 matching lines @@
       },
       {
         "test": "view_manager_unittests"
       },
       {
         "test": "views_unittests"
       },
       {
         "test": "wm_unittests"
       }
+    ],
+    "scripts": [
+      {
+        "name": "gn_check",
+        "script": "gn_check.py"
+      }
     ]
   }
 }