scope_exit: Make constexpr

Allows the use of the macro in constexpr-contexts.
Also avoids some potential problems when nesting braces inside it.

src/video_core/renderer_vulkan/present/layer.cpp

@@ -82,7 +82,9 @@ void Layer::ConfigureDraw(PresentPushConstants* out_push_constants,
     // Finish any pending renderpass
     scheduler.RequestOutsideRenderPassOperationContext();
     scheduler.Wait(resource_ticks[image_index]);
-    SCOPE_EXIT({ resource_ticks[image_index] = scheduler.CurrentTick(); });
+    SCOPE_EXIT {
+        resource_ticks[image_index] = scheduler.CurrentTick();
+    };
 
     if (!use_accelerated) {
         UpdateRawImage(framebuffer, image_index);