Add a flag to BUILDCONFIG for updating some global configs.

Add a flag to BUILDCONFIG for updating some global configs.

This is part one of a multi-way landing, as described in the comment for the added flag.

The patch that this enables is https://codereview.chromium.org/1324623005/ which will be landed after ffmpeg and WebKit have been updated.

Committed: https://crrev.com/96453de346274c747c13d89c2ffaf9a6ce0ba667
Cr-Commit-Position: refs/heads/master@{#347495}

[brettw, 2015-09-04 20:48:39]

brettw@chromium.org changed reviewers:
+ dpranke@chromium.org

[brettw, 2015-09-04 21:18:42]

The CQ bit was checked by brettw@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-09-04 21:18:50]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1312363011/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1312363011/20001

[Dirk Pranke, 2015-09-04 21:24:40]

lgtm

[brettw, 2015-09-04 21:25:08]

The CQ bit was unchecked by brettw@chromium.org

[brettw, 2015-09-04 21:25:09]

The CQ bit was checked by brettw@chromium.org

[commit-bot: I haz the power, 2015-09-04 21:25:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1312363011/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1312363011/20001

[commit-bot: I haz the power, 2015-09-04 21:53:06]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-09-04 21:53:47]

Patchset 2 (id:??) landed as
https://crrev.com/96453de346274c747c13d89c2ffaf9a6ce0ba667
Cr-Commit-Position: refs/heads/master@{#347495}