Apply patch from https://codereview.chromium.org/425333002 to gtest.gyp.

This may be required for https://codereview.chromium.org/425333002 to
land in Chromium.

TBR=machenbach@chromium.org

Review URL: https://codereview.chromium.org/448053002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22951 ce2b1a6d-e550-0410-aec6-3dcde31c8c00