Enhance the TD pass to build composite graphs when we have indirect call

Enhance the TD pass to build composite graphs when we have indirect call
sites that target multiple callees.  If we have a function table, for
example, with N callees, and M callers call through it, we used to have
to perform O(M*N) graph inlinings.  Now we perform O(M+N) inlinings.

This speeds up the td pass on perlbmk from 36.26s to 25.75s.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@20743 91177308-0d34-0410-b5e6-96231b3b80d8