buildsystem_sanity_check: whitelist Vagrantfiles
buildsystem_sanity_check: whitelist Vagrantfiles

Vagrantfiles are not part of our build-system so they should be ignored
by its sanity check.

OlegHahm/RIOT,ant9000/RIOT,jasonatran/RIOT,authmillenon/RIOT,authmillenon/RIOT,OlegHahm/RIOT,kYc0o/RIOT,jasonatran/RIOT,kYc0o/RIOT,miri64/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,ant9000/RIOT,authmillenon/RIOT,ant9000/RIOT,ant9000/RIOT,authmillenon/RIOT,kaspar030/RIOT,miri64/RIOT,miri64/RIOT,kYc0o/RIOT,ant9000/RIOT,OTAkeys/RIOT,jasonatran/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,OTAkeys/RIOT,miri64/RIOT,OTAkeys/RIOT,authmillenon/RIOT,kaspar030/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,kYc0o/RIOT,kaspar030/RIOT,kaspar030/RIOT,kaspar030/RIOT,miri64/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,OTAkeys/RIOT,jasonatran/RIOT