Remove one invocation of the ARC optimizer.
Remove one invocation of the ARC optimizer.

Removing one of the invocation of the ARC optimizer. I did not measure any
regressions on the performance test suite (using -O), but I did see a
reduction in compile time on rdar://24350646.

khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift