vo_gl: Fix libass subtitles disappearing during pause

EOSD bitmaps were not properly redrawn when the screen was updated
to change other OSD content, resulting in libass subtitles
disappearing if the OSD changed while paused. Fixed by adding a call
to redraw the EOSD part too.

libvo/vo_gl.c

@@ -1205,6 +1205,8 @@ static int control(uint32_t request, void *data)
     if (vo_doublebuffering)
       do_render();
     draw_osd();
+    if (vo_doublebuffering)
+      do_render_osd(2);
     flip_page();
     return VO_TRUE;
   }