Revert "Revert "Resubmit rL345008 "Split MachinePipeliner code into header and cpp files"""

This reverts commit rL350497
reported remaining issues seem to be unrelated to modules or this change.
more info: https://reviews.llvm.org/D56084

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350621 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed