Vulkan: Workaround ARM bug with stencil write mask Bug: angleproject:7556 Change-Id: I0aa17c178071cc15d8ee15f700b0c4932819c72a Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3821367 Reviewed-by: Ian Elliott <ianelliott@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Cody Northrop <cnorthrop@google.com>