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/testintersections.c

@@ -211,6 +211,7 @@ static void loop(void *arg)
     /* 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_MOUSE_BUTTON_DOWN:
             mouse_begin_x = event.button.x;