Looks like this pass isn't really used and hasn't been worked on in a
loooong time.
Reviewed By: asbirlea
Differential Revision: https://reviews.llvm.org/D89010
The LoopExtractor created new functions (by definition), which violates
the restrictions of a LoopPass.
The correct implementation of this pass should be as a ModulePass.
Includes reverting rL82990 implications on the LoopExtractor.
Fixes PR3082 and PR8929.
Differential Revision: https://reviews.llvm.org/D69069
