Fix many* python scripts in src/

gpu/command_buffer/build_gles2_cmd_buffer.py

Index: gpu/command_buffer/build_gles2_cmd_buffer.py
diff --git a/gpu/command_buffer/build_gles2_cmd_buffer.py b/gpu/command_buffer/build_gles2_cmd_buffer.py
index 36dad3fb048aa0f33455422f4a062e485176411a..9c7b758e1c812cb7ff9a7b1fd0888f6a06b3b316 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -1,5 +1,4 @@
-#!/usr/bin/python
-#
+#!/usr/bin/env python
 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
@@ -5984,7 +5983,9 @@ def main(argv):
 
   if gen.errors > 0:
     print "%d errors" % gen.errors
-    sys.exit(1)
+    return 1
+  return 0
+
 
 if __name__ == '__main__':
-  main(sys.argv[1:])
+  sys.exit(main(sys.argv[1:]))