[MCJIT] Reapply r222828 and r222810-r222812 with fix for MSVC move-op issues.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222840 91177308-0d34-0410-b5e6-96231b3b80d8
[MCJIT] Fix missing return statement.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222841 91177308-0d34-0410-b5e6-96231b3b80d8