Add the OpenGL renderer to the GN build. BUG=angle:890 Change-Id: I097296c7125e203ba04eab1c179dc8c183ed4789 Reviewed-on: https://chromium-review.googlesource.com/249842 Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>