[ORC] Generalize alias materialization to support re-exports (i.e. aliasing of
symbols in another VSO).

Also fixes a bug where chained aliases within a single VSO would deadlock on
materialization.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@336741 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed