cache: silence "EOF reached" message

This message will be printed relatively often once EOF is reached. In
some cases this is rather annoying, for example when playing HLS. (With
HLS, the stream is just a playlist file, while libavformat opens actual
media files without mpv's knowledge, so the cache is completely useless
and hits EOF instantly.)

That it retries reading is apparently a good thing: at least local files
can grow, and even after the player got the EOF, playback _could_ be
resumed by basically polling and detecting that there is more data. So
I'm not changing this behavior yet.

stream/cache.c

@@ -285,7 +285,7 @@ done:
     s->idle = s->eof;
     s->reads++;
     if (s->eof)
-        MP_VERBOSE(s, "EOF reached.\n");
+        MP_TRACE(s, "EOF reached.\n");
 
     pthread_cond_signal(&s->wakeup);