Summary:
In preparation for graph comparison and filtering, this is a library for
representing graphs in LLVM. This will enable easier encapsulation and reuse
of graphs in llvm-xray.
Depends on D28999, D28225
Reviewers: dblaikie, dberris
Reviewed By: dberris
Subscribers: mgorny, llvm-commits
Differential Revision: https://reviews.llvm.org/D29005
llvm-svn: 294713
