whoisd: improve debian postinst script
whoisd: improve debian postinst script

The script should return with 0 per default and it's nice to actually
look at the first argument so we know what is being asked of us (like
"configure") and not always run the same thing.

ettrig/NIPAP,plajjan/NIPAP,SpriteLink/NIPAP,SpriteLink/NIPAP,bbaja42/NIPAP,SpriteLink/NIPAP,SoundGoof/NIPAP,SoundGoof/NIPAP,SoundGoof/NIPAP,garberg/NIPAP,SoundGoof/NIPAP,bbaja42/NIPAP,garberg/NIPAP,fredsod/NIPAP,SoundGoof/NIPAP,plajjan/NIPAP,ettrig/NIPAP,ettrig/NIPAP,plajjan/NIPAP,fredsod/NIPAP,SpriteLink/NIPAP,bbaja42/NIPAP,bbaja42/NIPAP,garberg/NIPAP,fredsod/NIPAP,ettrig/NIPAP,plajjan/NIPAP,SpriteLink/NIPAP,ettrig/NIPAP,SpriteLink/NIPAP,plajjan/NIPAP,SoundGoof/NIPAP,garberg/NIPAP,plajjan/NIPAP,fredsod/NIPAP,fredsod/NIPAP,ettrig/NIPAP,fredsod/NIPAP,bbaja42/NIPAP,bbaja42/NIPAP,garberg/NIPAP,garberg/NIPAP