Rolls the build/ repos from Chromium to include the fixed config.
Also includes incidental improvements to platform-specific hooks.

Bug: chromium:727437
Change-Id: Ia42a30acac1e800e593e304bfc59d86eb0a1e57c
Reviewed-on: https://chromium-review.googlesource.com/782340
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>