Vulkan: Fix bug with ContextVk::mWaitSemaphores processing. Regression: 2e5ca217ca134a7ae4e241e2f7e4cfa637305af7 Vulkan: Let each current context has its own QueueSerial. Problem details: - Call to finishImpl()/flushImpl() will skip mWaitSemaphores processing when there are no pending commands. - finishImpl() will call clearAllGarbage() that will clear all mCurrentGarbage. - However, some mWaitSemaphores may be in the mCurrentGarbage (Semaphore created in SyncHelperNativeFence::serverWait()). Bug: angleproject:8007 Test: angle_end2end_tests --gtest_filter="EGLSyncTest.AndroidNativeFence_VkSemaphoreDestroyBug*" Change-Id: Ia51663eae739b505ca00437cea4ae71526dedbfb Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4225392 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Charlie Lao <cclao@google.com> Commit-Queue: Igor Nazarov <i.nazarov@samsung.com>