Fix goofy commentary in PPCTargetObjectFile.cpp.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181725 91177308-0d34-0410-b5e6-96231b3b80d8
[objc-arc-opts] Add comment to BBState making it clear that get{TopDown,BottomUp}PtrState will create a new PtrState object if it does not find a PtrState for Arg.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181726 91177308-0d34-0410-b5e6-96231b3b80d8