Rework the cflags test so it works cross platform.

Rather than using optimization flags to test cflags,
use our own explicit defined flag.  This is better than
depending on __OPTIMIZE__.

R=phajdan.jr@chromium.org, scottmg@chromium.org

Review URL: https://codereview.chromium.org/23140009

git-svn-id: http://gyp.googlecode.com/svn/trunk@1698 78cadc50-ecff-11dd-a971-7dbc132099af
3 files changed