[MachinePipeliner] Split MachinePipeliner code into header and cpp files

Split MachinePipeliner code into header and cpp files to allow inheritance from SwingSchedulerDAG

Differential Revision: https://reviews.llvm.org/D53477

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@345008 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed