Update the GLDEBUGPROC typedef to the latest spec version.

The non-const parameter was causing issues with ubsan because ANGLE is
compiled with lasted typedefs.

BUG=820848
TBR=piman@chromium.org

Cq-Include-Trybots: luci.chromium.try:linux_optional_gpu_tests_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I366e101fb8c42edec1d381e27cb55a51283f4e09
Reviewed-on: https://chromium-review.googlesource.com/969083
Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#545858}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 5b12500886c296204e21797b9ee078800c485c4f
1 file changed