Add a pass to overlay pic16 data sections for function frame and automatic

Add a pass to overlay pic16 data sections for function frame and automatic
variables. This pass can be invoked by llvm-ld or opt to traverse over the call graph
to detect what function frames and their automatic variables can be overlaid.
Currently this builds an archive , but needs to be changed to a loadable module.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84753 91177308-0d34-0410-b5e6-96231b3b80d8