Under ARC, when we're passing the address of a strong variable

Under ARC, when we're passing the address of a strong variable
to an out-parameter using the indirect-writeback conversion,
and we copied the current value of the variable to the temporary,
make sure that we register an intrinsic use of that value with
the optimizer so that the value won't get released until we have
a chance to retain it.

rdar://13195034

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177813 91177308-0d34-0410-b5e6-96231b3b80d8