command: fix subtitle selection display

Commit 9c02ae7e95 set the sh variable (see diff) to the struct of
type sh_sub instead the one of sh_stream. Unfortunately this didn't
crash, and merely made the OSD show "unknown" for the language.

Commit 804bf91570 accidentally removed the display of the track
title. Add it back.

command.c

@@ -1576,12 +1576,16 @@ static int mp_property_sub(m_option_t *prop, int action, void *arg,
             return M_PROPERTY_OK;
         }
         if (opts->sub_id >= 0 && mpctx->d_sub && mpctx->d_sub->sh) {
-            struct sh_stream *sh = mpctx->d_sub->sh;
+            struct sh_stream *sh = ((struct sh_sub *)mpctx->d_sub->sh)->gsh;
             char *lang = demuxer_stream_lang(mpctx->demuxer, sh);
             if (!lang)
                 lang = talloc_strdup(NULL, mp_gtext("unknown"));
-            *(char **) arg = talloc_asprintf(NULL, "(%d) %s", opts->sub_id,
-                                             lang);
+            if (sh->title)
+                *(char **)arg = talloc_asprintf(NULL, "(%d) %s (\"%s\")",
+                                                opts->sub_id, lang, sh->title);
+            else
+                *(char **) arg = talloc_asprintf(NULL, "(%d) %s", opts->sub_id,
+                                                 lang);
             talloc_free(lang);
             return M_PROPERTY_OK;
         }

libmpdemux/demuxer.h

@@ -136,7 +136,7 @@ typedef struct demux_stream {
 // ---- mov -----
     unsigned int ss_mul, ss_div;
 // ---- stream header ----
-    void *sh;
+    void *sh;              // points to sh_audio or sh_video
 } demux_stream_t;
 
 typedef struct demuxer_info {