In particular, into EngineBuilder. This should only impact
the private API between the EE and EB classes, not external
clients, since JITCtor and MCJITCtor are both protected members.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131317 91177308-0d34-0410-b5e6-96231b3b80d8