Android: another fix for perf tests.

Force "Release" build mode.
The bot needs to pass --release, this is a temporary workaround.

BUG=318369
TBR=frankf@chromium.org, tonyg@chromium.org, stip@chromium.org
NOTRY=True

Review URL: https://codereview.chromium.org/70103006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234803 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234803