The promised test case for r175939.

This test makes sure that the ObjCARC escape analysis looks at the uses of
instructions which copy the block pointer value by checking all four cases where
that can occur.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177232 91177308-0d34-0410-b5e6-96231b3b80d8