If we have an indirect call site that calls N functions, inline the N functions

into a temporary graph, remember it for later, then inline the tmp graph into
the call site.

In the case where there are other call sites to the same set of functions, this
permits us to just inline the temporary graph instead of all of the callees.

This turns N*M inlining situations into an N+M inlining situation.

llvm-svn: 20036