use shquote(3) for bsddiskname (aka packname)

Please enter a name for your NetBSD disk

I chose:

	Jeremy's Disk

disklabel errored as it had that bogus name with a single quote in it.

I have no idea if that is even a valid name. But anyways it should choke 
the way it did.

I don't see shquote(3) used by NetBSD. But maybe that should be used for 
bsddiskname in disks.c.

  Jeremy C. Reed