Re-commit optimization bisect support (r267022) without new pass manager support.

The original commit was reverted because of a buildbot problem with LazyCallGraph::SCC handling (not related to the OptBisect handling).

Differential Revision: http://reviews.llvm.org/D19172



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@267231 91177308-0d34-0410-b5e6-96231b3b80d8
96 files changed