headers: Fix vulkan.hpp clang compiler errors
headers: Fix vulkan.hpp clang compiler errors

Change-Id: Ibca9f31b722945f1d96fb41aca0f1e78bd6567f1

KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools