player: free subtitle renderer on exit

This was probably commented as an oversight. Since the subtitle renderer
was uninitialized on reinitialization anyway, this had no negative
consequences, except a memory on exit.

player/loadfile.c

@@ -1231,7 +1231,7 @@ terminate_playback:
     uninit_audio_chain(mpctx);
     uninit_video_chain(mpctx);
     uninit_sub_all(mpctx);
-    //uninit_sub_renderer(mpctx);
+    uninit_sub_renderer(mpctx);
     uninit_demuxer(mpctx);
     uninit_stream(mpctx);
     if (!opts->fixed_vo)