Backed out the viewport and cliprect changes in 9fb5a9ccac

This ended up being lots of application code churn without any real benefit in practice.

test/testrelative.c

@@ -52,7 +52,7 @@ static void loop(void)
         }
     }
     for (i = 0; i < state->num_windows; ++i) {
-        SDL_FRect viewport;
+        SDL_Rect viewport;
         SDL_Renderer *renderer = state->renderers[i];
         if (state->windows[i] == NULL) {
             continue;