Library Forwarding/vulkan: Fix query of vkCreateInstance function poi…

…nter

The Vulkan specification states that "global commands" like vkCreateInstance
may only be queried with a NULL instance. Some implementations return null
pointers otherwise.

Fixes #3519.

ThunkLibs/libvulkan/Host.cpp

@@ -39,7 +39,8 @@ static void DoSetupWithInstance(VkInstance instance) {
     }
 
     // Query pointers for functions customized below
-    (void*&)LDR_PTR(vkCreateInstance) = (void*)LDR_PTR(vkGetInstanceProcAddr)(instance, "vkCreateInstance");
+    // NOTE: The Vulkan specification requires vkCreateInstance to be queried with a nullptr parameter.
+    (void*&)LDR_PTR(vkCreateInstance) = (void*)LDR_PTR(vkGetInstanceProcAddr)(nullptr, "vkCreateInstance");
     (void*&)LDR_PTR(vkCreateDevice) = (void*)LDR_PTR(vkGetInstanceProcAddr)(instance, "vkCreateDevice");
 
     // Only do this lookup once.