* 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>