Vulkan: Safer struct initialization Using x = {}; before filling out each field, we can be sure any missing field is 0 initialized. This in turn helps us not have to specify certain fields that are generally unused (at the moment), such as pNext. Bug: angleproject:2860 Change-Id: Ia1fa2db3ecfb316673a02ac0c5e13e47e055a19f Reviewed-on: https://chromium-review.googlesource.com/c/1259764 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>