Make run_code_generation fail if git cl format fails.

The lack of error code was hiding errors in the Skia auto-roller.

Bug: skia:9812
Change-Id: Ib43e5eb1749161e9fa0186bfd4a293dadaf82f8a
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2024178
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>

scripts/run_code_generation.py

@@ -232,7 +232,8 @@ def main():
         # line length limits. Work around this by calling git cl format with --full.
         args += ['cl', 'format', '--full']
         print('Calling git cl format')
-        subprocess.call(args)
+        if subprocess.call(args) != 0:
+            sys.exit(1)
 
         # Update the output hashes again since they can be formatted.
         for name, script in sorted(generators.iteritems()):