Extracted ObjCARC.cpp into its own library libLLVMObjCARCOpts in preparation for refactoring the ARC Optimizer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173647 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/opt/opt.cpp b/tools/opt/opt.cpp
index a73525f..81a2de2 100644
--- a/tools/opt/opt.cpp
+++ b/tools/opt/opt.cpp
@@ -567,6 +567,7 @@
   PassRegistry &Registry = *PassRegistry::getPassRegistry();
   initializeCore(Registry);
   initializeScalarOpts(Registry);
+  initializeObjCARCOpts(Registry);
   initializeVectorization(Registry);
   initializeIPO(Registry);
   initializeAnalysis(Registry);