Add a simple pass to make sure that all (non-library) calls to malloc and free

Add a simple pass to make sure that all (non-library) calls to malloc and free
are visible to analysis as intrinsics.  That is, make sure someone doesn't pass
free around by address in some struct (as happens in say 176.gcc).

This doesn't get rid of any indirect calls, just ensure calls to free and malloc
are always direct.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@27560 91177308-0d34-0410-b5e6-96231b3b80d8