[gn] Switch off gyp in runhooks by default

gypfiles/gyp_v8

Index: gypfiles/gyp_v8
diff --git a/gypfiles/gyp_v8 b/gypfiles/gyp_v8
index 8be39d961536f186e7da7d3440dd28d5e27055a6..b8b5f742b1e27dee104aa116a44efd6091f8bd09 100755
--- a/gypfiles/gyp_v8
+++ b/gypfiles/gyp_v8
@@ -118,10 +118,22 @@ def run_gyp(args):
 if __name__ == '__main__':
   args = sys.argv[1:]
 
-  if int(os.environ.get('GYP_CHROMIUM_NO_ACTION', 0)):
+  gyp_chromium_no_action = os.environ.get('GYP_CHROMIUM_NO_ACTION')
+  if gyp_chromium_no_action == '1':
     print 'Skipping gyp_v8 due to GYP_CHROMIUM_NO_ACTION env var.'
     sys.exit(0)
 
+  running_as_hook = '--running-as-hook'
+  if running_as_hook in args and gyp_chromium_no_action != '0':
+    print 'GYP is now disabled by default in runhooks.\n'
+    print 'If you really want to run this, either run '
+    print '`python gypfiles/gyp_v8` explicitly by hand '
+    print 'or set the environment variable GYP_CHROMIUM_NO_ACTION=0.'
+    sys.exit(0)
+
+  if running_as_hook in args:
+    args.remove(running_as_hook)
+
   gyp_environment.set_environment()
 
   # This could give false positives since it doesn't actually do real option