Revert the workaround and fix it properly by passing the
additional necessary flag to the compiler.

BUG=libyuv:700

Change-Id: I1c893a8acb5079decbee6963b689424bf2f99f4f
Reviewed-on: https://chromium-review.googlesource.com/487881Reviewed-by: Frank Barchard <fbarchard@google.com>