MacGui: Fix issue when selecting a preset with multiple audio tracks (ie. AppleTV...

MacGui: Fix issue when selecting a preset with multiple audio tracks (ie. AppleTV preset) any track after the first track used the first source track which would cause track mismatches. Now if the first track is set to use source track 3 for instance, the seond track will use source track 3 as well.
- Fixes issue where the AppleTv Preset would use a different source track for its AC3 track than the first aac track on some multiple track sources.
- Addresses the bug explained here http://forum.handbrake.fr/viewtopic.php?f=12&t=15854

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@3202 b64f7644-9d1e-0410-96f1-a4d463321fa5