Summary: When LLVM/Clang is built without ARM support, the ios_kext runtime
library is not built, but without this patch, the Makefile still tries to
copy it. This is a recent regression, because the ios_kext library used
to also be built on x86_64.

Reviewers: beanz

Subscribers: aemerson, cfe-commits, rengolin

Differential Revision: http://reviews.llvm.org/D13421

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@249281 91177308-0d34-0410-b5e6-96231b3b80d8