Add a script to run "gclient config" and edit the output, since
gclient will no longer do what we want.

BUG=angleproject:1204
TEST=none

Change-Id: I00e214490967e14034c935e051acc39229f27ff7
Reviewed-on: https://chromium-review.googlesource.com/312233Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Frank Henigman <fjhenigman@chromium.org>