VK_ONLY_EXPORTED_PROTOTYPES

If the VK_ONLY_EXPORTED_PROTOTYPES macro is defined by an application at compile time, only prototypes for Vulkan APIs tagged as `"exported"`in the API XML will be included. For non-tagged APIs, only typedefs for API function pointers will be defined.

This is intended to match APIs which are statically exported by the Vulkan loader. At present, the exported APIs are only those defined by Vulkan core versions.

If the macro is not defined by the application, prototypes for all Vulkan APIs will be included.