[ORC] fix use-after-move. NFC

Summary:
scan-build flagged a potential use-after-move in debug builds.  It's not
safe that a moved from value contains anything but garbage.  Manually
DRY up these repeated expressions.

Reviewers: lhames

Reviewed By: lhames

Subscribers: hiraditya, llvm-commits, srhines

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62112

llvm-svn: 361203