SetDefaultGetInstanceProcAddr doesn't work on MacOS

[Nv7-GitHub]

Using SetDefaultGetInstanceProcAddr on MacOS just causes the error vulkan: error loading default getProcAddr. This is because:

1. First, this function calls setDefaultProcAddr

   vulkan/init.go

   Line 22 in 956e385

   C.setDefaultProcAddr()

2. In setDefaultProcAddr, it calls getDefaultProcAddr

   vulkan/vk_wrapper_desktop.c

   Line 14 in 956e385

   getInstanceProcAddress = getDefaultProcAddr();

3. In getDefaultProcAddr, for MacOS, it just returns NULL

   vulkan/vk_default_loader.c

   Lines 35 to 37 in 956e385

   	#elif defined(__APPLE__) && defined(__MACH__)
   	// return &loaderWrap;
   	return NULL;

4. In SetDefaultGetInstanceProcAddr, it checks for isProcAddrSet

   vulkan/init.go

   Lines 23 to 25 in 956e385

   	if C.isProcAddrSet() == 0 {
   	return errors.New("vulkan: error loading default getProcAddr")
   	}

5. In isProcAddrSet, it checks if it is equal to NULL

   vulkan/vk_wrapper_desktop.c

   Line 18 in 956e385

   return getInstanceProcAddress == NULL ? 0 : 1;

Therefore, on MacOS, isProcAddrSet will always return false. Why is it like this? Is there a way to get around this error? If you ignore it, you just get an error about proc addr not being set in Init.