[PM] Add support for building a default AA pipeline to the PassBuilder.

Pretty boring and lame as-is but necessary. This is definitely a place
we'll end up with extension hooks longer term. =]

Differential Revision: https://reviews.llvm.org/D28076

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@290449 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed