[PM] Move the analysis registry into the Passes.cpp file and provide

a normal interface for it in Passes.h.

This gives us essentially a single interface for running pass managers
which are provided from the bottom of the LLVM stack through interfaces
at the top of the LLVM stack that populate them with all of the
different analyses available throughout. It also means there is a single
blob of code that needs to include all of the pass headers and needs to
deal with the registry of passes and parsing names.

No functionality changed intended, should just be cleanup.

llvm-svn: 225237