MacGui: removed the “Large file size” checkbox.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6349 b64f7644-9d1e-0410-96f1-a4d463321fa5
MacGui: replaced the last two NSBeginCriticalAlertSheet calls, and two NSEnumerators.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6350 b64f7644-9d1e-0410-96f1-a4d463321fa5