Vulkan: Deduplicate sync's clientWait logic As a side effect, both GL_NV_fence's client wait and external fence client wait is also done in an unlocked tail call. Bug: angleproject:8340 Change-Id: Ia0b882cc67ecf7ac5b2a8f9dc9e721060cca3c9e Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4908351 Reviewed-by: mohan maiya <m.maiya@samsung.com> Reviewed-by: Charlie Lao <cclao@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>