Vulkan: Only attempt to create a CAMetalLayer on macOS

Source/Core/VideoBackends/Vulkan/VKMain.cpp

@@ -259,6 +259,10 @@ void VideoBackend::Shutdown()
 void VideoBackend::PrepareWindow(WindowSystemInfo& wsi)
 {
 #if defined(VK_USE_PLATFORM_METAL_EXT)
+  // We only need to manually create the CAMetalLayer on macOS.
+  if (wsi.type != WindowSystemType::MacOS)
+    return;
+
   // This is kinda messy, but it avoids having to write Objective C++ just to create a metal layer.
   id view = reinterpret_cast<id>(wsi.render_surface);
   Class clsCAMetalLayer = objc_getClass("CAMetalLayer");