tests: Fix tests when run with the --high-pixel-density flag

Scales pointer coordinates where needed to fix the following tests when run with the --high-pixel-density flag:

- testaudio
- testaudiostreamdynamicresample
- testhittesting
- testintersections
- testmanymouse
- testoverlay
- testwm

test/testoverlay.c

@@ -255,6 +255,7 @@ static void loop(void)
     /* Check for events */
     while (SDL_PollEvent(&event)) {
         SDLTest_CommonEvent(state, &event, &done);
+        SDL_ConvertEventToRenderCoordinates(SDL_GetRenderer(SDL_GetWindowFromEvent(&event)), &event);
 
         switch (event.type) {
         case SDL_EVENT_WINDOW_RESIZED: