Fix an unused variable warning that Chad noticed.

llvm-svn: 148164
diff --git a/llvm/lib/Transforms/Scalar/ObjCARC.cpp b/llvm/lib/Transforms/Scalar/ObjCARC.cpp
index 0cf3148..756e565 100644
--- a/llvm/lib/Transforms/Scalar/ObjCARC.cpp
+++ b/llvm/lib/Transforms/Scalar/ObjCARC.cpp
@@ -616,7 +616,7 @@
       const User *UUser = *UI;
       // Special - Use by a call (callee or argument) is not considered
       // to be an escape.
-      if (ImmutableCallSite CS = cast<Value>(UUser))
+      if (isa<CallInst>(UUser) || isa<InvokeInst>(UUser))
         continue;
       if (isa<BitCastInst>(UUser) || isa<GetElementPtrInst>(UUser) ||
           isa<PHINode>(UUser) || isa<SelectInst>(UUser)) {