Add GLES1 targets and stub entry points. * Create a new libGLESv1_CM target. * Merge all autogenerated extension entry points into one file. * Allow creation of ES1 contexts. BUG=angleproject:2306 Change-Id: I446258363a96a3c37d657089dd7c1cff0fa3cf78 Reviewed-on: https://chromium-review.googlesource.com/865718 Commit-Queue: Geoff Lang <geofflang@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>