vulkan: define VK_NO_PROTOTYPES

This just disables the vulkan headers from defining any symbols
like vkCmdPipelineBarrier2(). Instead, all functions must be loaded
via the loader and used as function pointers as vk->CmdPipelineBarrier2.

Mostly just forces developers to write correct code, as using the
symbols can be undesirable in case API users define their own
function wrappers via the loader API.

libavutil/vulkan.h

@@ -19,6 +19,8 @@
 #ifndef AVUTIL_VULKAN_H
 #define AVUTIL_VULKAN_H
 
+#define VK_NO_PROTOTYPES
+
 #include "pixdesc.h"
 #include "bprint.h"
 #include "hwcontext.h"