tools: reduce verbosity of cpplint

Every time `make test` is run, the cpplint prints the file it
successfully linted. None of the other linters in the project does
that. This patch simply removes the "Done processing" message from the
cpplint.

PR-URL: https://github.com/nodejs/node/pull/5578


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Michaël Zasso <mic.besace@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>