[clang-tidy] Fix broken test with redundant string init (msvc).

Summary:
There is a silly bug that got introduced after fixing incorrect paths with this patch:
http://reviews.llvm.org/D18293

The tests was present twice in the file.

Reviewers: alexfh, rnk

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D18365

llvm-svn: 264080