cpp11-migrate: Fix silly logic error preventing multiple transforms

A missed clause in an error test added in r188371 caused any use of the
migrator requesting multiple transforms to fail.



git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@188374 91177308-0d34-0410-b5e6-96231b3b80d8