Make dumpPassStructure be a PMDataManager abstraction, rather than

Make dumpPassStructure be a PMDataManager abstraction, rather than
a Pass abstraction, since that's the level it's actually used at.
Rename Pass' dumpPassStructure to dumpPass.

This eliminates an awkward use of getAsPass() to convert a PMDataManager*
into a Pass* just to permit a dumpPassStructure call.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111199 91177308-0d34-0410-b5e6-96231b3b80d8