We were missing one warning diable flag, for bison compatiblity,
and were missing the appropriate flag to enable c++11 support.

BUG=angle:773

Change-Id: I717ead6e1726920a6c28559503cb98e94dc29c16
Reviewed-on: https://chromium-review.googlesource.com/238449Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>