gnrc_netif: generalise address search functions
gnrc_netif: generalise address search functions

    Reduce code duplication by combining internal helper functions
    that either loop over interface addresses or multicast groups.

aeneby/RIOT,OlegHahm/RIOT,kYc0o/RIOT,OlegHahm/RIOT,lazytech-org/RIOT,BytesGalore/RIOT,josephnoir/RIOT,toonst/RIOT,A-Paul/RIOT,aeneby/RIOT,biboc/RIOT,kYc0o/RIOT,biboc/RIOT,BytesGalore/RIOT,OTAkeys/RIOT,authmillenon/RIOT,lazytech-org/RIOT,x3ro/RIOT,mfrey/RIOT,ant9000/RIOT,authmillenon/RIOT,jasonatran/RIOT,mtausig/RIOT,gebart/RIOT,RIOT-OS/RIOT,miri64/RIOT,authmillenon/RIOT,ant9000/RIOT,ant9000/RIOT,rfuentess/RIOT,avmelnikoff/RIOT,rfuentess/RIOT,OlegHahm/RIOT,x3ro/RIOT,OlegHahm/RIOT,BytesGalore/RIOT,josephnoir/RIOT,toonst/RIOT,mfrey/RIOT,josephnoir/RIOT,avmelnikoff/RIOT,A-Paul/RIOT,miri64/RIOT,basilfx/RIOT,smlng/RIOT,toonst/RIOT,RIOT-OS/RIOT,A-Paul/RIOT,mtausig/RIOT,biboc/RIOT,cladmi/RIOT,kbumsik/RIOT,BytesGalore/RIOT,OTAkeys/RIOT,miri64/RIOT,BytesGalore/RIOT,yogo1212/RIOT,mtausig/RIOT,smlng/RIOT,yogo1212/RIOT,kaspar030/RIOT,mtausig/RIOT,josephnoir/RIOT,yogo1212/RIOT,rfuentess/RIOT,lazytech-org/RIOT,biboc/RIOT,smlng/RIOT,mfrey/RIOT,lazytech-org/RIOT,kbumsik/RIOT,x3ro/RIOT,kbumsik/RIOT,authmillenon/RIOT,kaspar030/RIOT,cladmi/RIOT,mtausig/RIOT,RIOT-OS/RIOT,kYc0o/RIOT,avmelnikoff/RIOT,yogo1212/RIOT,cladmi/RIOT,kYc0o/RIOT,aeneby/RIOT,basilfx/RIOT,RIOT-OS/RIOT,x3ro/RIOT,A-Paul/RIOT,yogo1212/RIOT,gebart/RIOT,gebart/RIOT,avmelnikoff/RIOT,basilfx/RIOT,miri64/RIOT,mfrey/RIOT,authmillenon/RIOT,kbumsik/RIOT,toonst/RIOT,mfrey/RIOT,kbumsik/RIOT,smlng/RIOT,gebart/RIOT,OlegHahm/RIOT,OTAkeys/RIOT,kaspar030/RIOT,basilfx/RIOT,RIOT-OS/RIOT,miri64/RIOT,yogo1212/RIOT,gebart/RIOT,toonst/RIOT,jasonatran/RIOT,kaspar030/RIOT,ant9000/RIOT,aeneby/RIOT,rfuentess/RIOT,authmillenon/RIOT,kaspar030/RIOT,lazytech-org/RIOT,josephnoir/RIOT,OTAkeys/RIOT,x3ro/RIOT,rfuentess/RIOT,kYc0o/RIOT,biboc/RIOT,aeneby/RIOT,jasonatran/RIOT,ant9000/RIOT,A-Paul/RIOT,OTAkeys/RIOT,cladmi/RIOT,cladmi/RIOT,jasonatran/RIOT,smlng/RIOT,avmelnikoff/RIOT,basilfx/RIOT,jasonatran/RIOT