Add custom compiler flags to instrumented libraries build script.

Needed for gtk and potentially other libs.

BUG=313751
R=glider@chromium.org

Review URL: https://codereview.chromium.org/103783006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242460 0039d316-1c4b-4281-b951-d872f2087c98
Blink roll 164307:164321

http://build.chromium.org/f/chromium/perf/dashboard/ui/changelog_blink.html?url=/trunk&range=164308:164321&mode=html
TBR=
BUG=

Review URL: https://codereview.chromium.org/117333010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242461 0039d316-1c4b-4281-b951-d872f2087c98
Update .DEPS.git

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242462 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242462