MacGui: fixed a issue that happened on 10.8 when reloading a job from the queue: we tried to add an object to an immutable NSArray that for some reason known to the Cocoa framework was a NSMutableArray on 10.9+ , but not on 10.8.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6496 b64f7644-9d1e-0410-96f1-a4d463321fa5
MacGui: removed two useless array creation and made a copy of the trackSelectionLanguages ivar before assigning it to the preset dict.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6497 b64f7644-9d1e-0410-96f1-a4d463321fa5