[clang-tidy] Fix NOLINT test

Summary:
Test cases I've added in review D26218 were too brittle and weren't working properly.
This patch fixes this.

Reviewers: alexfh

Reviewed By: alexfh

Subscribers: cfe-commits

Patch by Nikita Kakuev!

Differential Revision: https://reviews.llvm.org/D26466

llvm-svn: 292926