cpp11-migrate: Add missing file headers in unit tests

Differential: http://llvm-reviews.chandlerc.com/D1124
Author: Guillaume Papin <guillaume.papin@epitech.eu>



git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@186093 91177308-0d34-0410-b5e6-96231b3b80d8