This makes us no longer relying on move-construction elision by the compiler. Suggested by D. Blaikie. From: Mehdi Amini <mehdi.amini@apple.com> git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@264475 91177308-0d34-0410-b5e6-96231b3b80d8