Don't complain about -fobjc-link-runtime being unused with -fobjc-arc.

If you build with -fobjc-arc, then -fobjc-link-runtime is implied but we
don't need to warn about it being unused in that case.  rdar://12039965

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@161444 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed