Bug 1524444 - Respect -n for linting in py3/py2 and better support it in other linters. r=ahal

Differential Revision: https://phabricator.services.mozilla.com/D6847

--HG--
extra : moz-landing-system : lando

python/mozlint/mozlint/types.py

@@ -40,6 +40,8 @@ class BaseType(object):
                 config.get('extensions', []),
             )
             config['exclude'] = exclude
+        elif config.get('exclude'):
+            del config['exclude']
 
         if not paths:
             return