Currently if you use -{start,stop}-{before,after}, it picks
the first instance with the matching pass name. If you run
the same pass multiple times, there's no way to distinguish them.
Allow specifying a run index wih ,N to specify which you mean.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@348285 91177308-0d34-0410-b5e6-96231b3b80d8
