Run check_gn_headers on ClangToTLinux

BUG=733500

Change-Id: Iee053126ab61bdb99ba78bdc74e720ff179febc6
Reviewed-on: https://chromium-review.googlesource.com/567729Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486770}

testing/buildbot/chromium.fyi.json

@@ -4199,6 +4199,14 @@
       }
     ]
   },
+  "ClangToTLinux": {
+    "scripts": [
+      {
+        "name": "check_gn_headers",
+        "script": "check_gn_headers.py"
+      }
+    ]
+  },
   "ClangToTLinux tester": {
     "gtest_tests": [
       {

testing/scripts/check_gn_headers.py

@@ -44,4 +44,4 @@ if __name__ == '__main__':
     'run': main_run,
     'compile_targets': main_compile_targets,
   }
-  sys.exit(common.run_script(sys.argv[1:], funcs))
+  common.run_script(sys.argv[1:], funcs)