UPSTREAM: egl/main: Add bits for EGL_KHR_mutable_render_buffer

A follow-up patch enables EGL_KHR_mutable_render_buffer for Android.
This patch is separate from the Android patch because I think it's
easier to review the platform-independent bits separately.

Reviewed-by: Tapani Plli <tapani.palli@intel.com>
(cherry picked from commit 3dc22381fa6ae6e5964908490f65e2903bd1b38d)

BUG=b:77899911
TEST=No android-cts-7.1 regressions on Eve.

Change-Id: Ibeea2e2c07f72a6a58d03cbd120bcc92687041a7
Reviewed-on: https://chromium-review.googlesource.com/1157105
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Chad Versace <chadversary@chromium.org>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
5 files changed