[clang-tidy] Do not list enabled checks when -quiet is given to run-clang-tidy.
Summary: When run-clang-tidy is given the -quiet flag, do not output the potentially hundreds of enabled check names at the beginning.
Patch by svenpanne.
Reviewers: alexfh, JonasToth
Reviewed By: JonasToth
Subscribers: JonasToth, cfe-commits
Differential Revision: https://reviews.llvm.org/D61849