Make glClearColor/Depth/Stencil entry points lockless These entry points only set state that is entirely accessed by the owning context and thus don't require locking. Bug: angleproject:8224 Change-Id: I6cddee865ffd38e228f8f87dd14adffb916e0fed Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4658172 Reviewed-by: Igor Nazarov <i.nazarov@samsung.com> Reviewed-by: Charlie Lao <cclao@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>