Compatibility fix with old sdks where VK_ERROR_UNKNOWN is not defined
Compatibility fix with old sdks where VK_ERROR_UNKNOWN is not defined

GPUOpen-LibrariesAndSDKs/VulkanMemoryAllocator,GPUOpen-LibrariesAndSDKs/VulkanMemoryAllocator,GPUOpen-LibrariesAndSDKs/VulkanMemoryAllocator