Improve testgles2 exit behavior (useful on Android)

test/testgles2.c

@@ -629,7 +629,7 @@ main(int argc, char *argv[])
     while (!done) {
         /* Check for events */
         ++frames;
-        while (SDL_PollEvent(&event)) {
+        while (SDL_PollEvent(&event) && !done) {
             switch (event.type) {
             case SDL_WINDOWEVENT:
                 switch (event.window.event) {
@@ -654,6 +654,7 @@ main(int argc, char *argv[])
             }
             SDLTest_CommonEvent(state, &event, &done);
         }
+        if (!done) {
           for (i = 0; i < state->num_windows; ++i) {
               status = SDL_GL_MakeCurrent(state->windows[i], context[i]);
               if (status) {
@@ -666,6 +667,7 @@ main(int argc, char *argv[])
               SDL_GL_SwapWindow(state->windows[i]);
           }
         }
+    }
 
     /* Print out some timing information */
     now = SDL_GetTicks();