Vulkan: Handle the case that VkEvent failed to create. If VkEvent failed to create, we can still fall back to pipeline barrier. This CL changes RefCountedEvent::init to return boolean. Also when it fail, this CL did an immediate garbage clean up in case it will free up more event from garbage list and then retry again. Bug: b/336844257 Change-Id: I28251849a92d1785701c55eb028a8fed63cfc372 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5532869 Commit-Queue: Charlie Lao <cclao@google.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Amirali Abdolrashidi <abdolrashidi@google.com>