[iOS] Enable ARC for CMake build (#67884)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/67884
Test Plan: Imported from OSS
Reviewed By: husthyc
Differential Revision: D32191532
Pulled By: xta0
fbshipit-source-id: a295004f8e7f1b0f5a4ab12ffd9b37c36b80226b
