This script calls all the various GL and back-end python scripts to
generate our internal format tables and entry points, etc. It uses
a GYP-like scheme of inputs/outputs to check modified time before
running the generators. It also will automatically call 'git cl
format' if any generator was called.

Also updates the copyright in a couple of touched files.

BUG=angleproject:2207

Change-Id: I4187a7622accc1c97a8d779b8f87fe00b74855ea
Reviewed-on: https://chromium-review.googlesource.com/742372
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>