Don't compile Metal stuff on iOS simulator.

git-svn-id: http://svn.purei.org/palleon/trunk@282 e658db38-2ae6-4b1c-8a17-0a8554443f32
Don't compile Metal stuff on iOS simulator.

git-svn-id: http://svn.purei.org/palleon/trunk@283 e658db38-2ae6-4b1c-8a17-0a8554443f32
Cleanup.

git-svn-id: http://svn.purei.org/palleon/trunk@284 e658db38-2ae6-4b1c-8a17-0a8554443f32