X11 - Linux - Fix for orphan window when destroying and recreating game class

[blakeb211]

Inside of olc::Platform_Linux, destroying a PGE class and then constructing a new one leaves an orphan window.

This patch fixed it for me, but this might be causing a segfault at full program termination. This is not an issue for me right now, but might be worth a look 🤷‍♂️

virtual olc::rcode ApplicationCleanUp() override
{
      XDestroyWindow(olc_Display, olc_Window);
      /* Patch start - Sync and flush X11 window manager */
      XSync(olc_Display, False); 
      X11::XEvent ev;
      while (XPending(olc_Display)) {
        XNextEvent(olc_Display, &ev);
      }
      /* Patch end */
      return olc::rcode::OK;
}

olcPGE v2.30
PopOS (Ubuntu variant) 24.04LTS.