arclint: add traprain-common directory

Reviewed-by: Philip Withnall <philip.withnall@collabora.co.uk>
Signed-off-by: Frédéric Dalleau <frederic.dalleau@collabora.com>
Differential Revision: https://phabricator.apertis.org/D4913

.arclint

@@ -3,7 +3,7 @@
      "clang-format-default": {
        "type": "clang-format",
        "version": ">=3.7.0",
-       "include": "(^(traprain-service|traprain-client|tests|mock-service|traprain-guidance)/.*\\.(c|h)$)"
+       "include": "(^(traprain-service|traprain-client|tests|mock-service|traprain-guidance|traprain-common)/.*\\.(c|h)$)"
      },
     "pep8-default": {
       "type": "pep8",