[Vulkan] Only require surface extensions on windows

src/xenia/ui/vulkan/vulkan_provider.cc

@@ -50,10 +50,12 @@ bool VulkanProvider::Initialize() {
   instance_ = std::make_unique<VulkanInstance>();
 
   // Always enable the swapchain.
+#if XE_PLATFORM_WIN32
   instance_->DeclareRequiredExtension("VK_KHR_surface", Version::Make(0, 0, 0),
                                       false);
   instance_->DeclareRequiredExtension("VK_KHR_win32_surface",
                                       Version::Make(0, 0, 0), false);
+#endif
 
   // Attempt initialization and device query.
   if (!instance_->Initialize()) {