Restructure PEI code:

- moved shrink wrapping code from PrologEpilogInserter.cpp to
  new file ShrinkWrapping.cpp.

- moved PEI pass definition into new shared header PEI.h.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71588 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed