[MustExecute] Use the annotation style printer

As suggested in the original review (https://reviews.llvm.org/D44524), use an annotation style printer instead.

Note: The switch from -analyze to -disable-output in tests was driven by the fact that seems to be the idiomatic style used in annoation passes.  I tried to keep both working, but the old style pass API for printers really doesn't make this easy.  It invokes (runOnFunction, print(Module)) repeatedly.  I decided the extra state wasn't worth it given the old pass manager is going away soonish anyway.
llvm-svn: 328015