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: #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>

tools/cpplint.py

@@ -3024,9 +3024,6 @@ def ProcessFile(filename, vlevel):
             'One or more unexpected \\r (^M) found;'
             'better to use only a \\n')
 
-  if not _cpplint_state.output_format == 'tap':
-    sys.stderr.write('Done processing %s\n' % filename)
-
 
 def PrintUsage(message):
   """Prints a brief usage string and exits, optionally with an error message.