[clang-tidy] Removed superfluous and slightly annoying newlines in run-clang-tidy's output.

Summary: The output of clang-tidy itself already has enough newlines, so the resulting output is more in line with the usual compiler output.

Patch by svenpanne.

Reviewers: alexfh, JonasToth

Reviewed By: JonasToth

Subscribers: JonasToth, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D61850

llvm-svn: 360883