player/loadfile: prefer non-image when selecting video track

This fixes `ytdl_hook`, which would start playback with the thumbnail
track selected. This issue occurs because the thumbnail track is added
first. If the main track is not marked as default afterward, which it
isn't for single streams, the first track (the image track) would be
selected.

In general, if a non-image track is available, it should be preferred.

player/loadfile.c

@@ -491,6 +491,8 @@ static bool compare_track(struct track *t1, struct track *t2, char **langs, bool
         return l1 > l2;
     if (t1->attached_picture != t2->attached_picture)
         return !t1->attached_picture;
+    if (t1->image != t2->image)
+        return !t1->image;
     if (t1->stream && t2->stream && opts->hls_bitrate >= 0 &&
         t1->stream->hls_bitrate != t2->stream->hls_bitrate)
     {