Don't use Twine objects after their lifetimes end.

No test, since it would depend on what the compiler can optimize/reuse.
My next commit made this bug visible on Linux Release compiles with some
versions of gcc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@251909 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed