[Bitcode] Fix bitcode compatibility issue with clang.arc.use intrinsic

[Bitcode] Fix bitcode compatibility issue with clang.arc.use intrinsic

Summary:
In r349534, objc arc implementation is switched to use intrinsics and at
the same time, clang.arc.use is renamed to llvm.objc.clang.arc.use to
make the naming more consistent. The side-effect of that is llvm no
longer recognize it as intrinsics and codegen external references to
it instead.

Rather than upgrade the old intrinsics name to the new one and wait for
the arc-contract pass to remove it, simply remove it in the bitcode
upgrader.

rdar://problem/48607063

Reviewers: pete, ahatanak, erik.pilkington, dexonsmith

Reviewed By: pete, dexonsmith

Subscribers: jkorous, jdoerfert, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59112

llvm-svn: 355663