Add --ignore to gclient recurse

Add --ignore to gclient recurse

This permits running git grep over the dependencies. With --ignore, gclient
recurse continues even if nothing is found in a dependency. Without this flag,
git grep returns 1 when nothing is found, causing gclient to stop processing the
remaining dependencies.

TBR=nsylvain@chromium.org
BUG=
TEST=


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=124914

[commit-bot: I haz the power, 2012-03-05 00:37:10]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/maruel@chromium.org/9600010/1

[commit-bot: I haz the power, 2012-03-05 00:43:08]

Change committed as 124914

[nsylvain, 2012-03-05 20:06:16]

lgtm