MacGui: stop before the last ("None") subtitle track when converting incompatible tracks to burn-in.

We were calling [[tempObject objectForKey:@"subtitleSourceTrackType"] intValue], so for "None", [nil intValue], which was returning 0. As it turns out, VOBSUB == 0 thus hb_subtitle_can_pass() was true out of sheer luck.

In a case where e.g. hb_subtitle_can_pass(VOBSUB, mux) is false (such as with the upcoming HB_MUX_AV_MP4 muxer), the None track would actually be deleted!



git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@5453 b64f7644-9d1e-0410-96f1-a4d463321fa5