afs: Always build address lists using the helper functions

afs: Always build address lists using the helper functions

Make the address list string parser use the helper functions for adding
addresses to an address list so that they end up appropriately sorted.
This will better handles overruns and make them easier to compare.

It also reduces the number of places that addresses are handled, making it
easier to fix the handling.

Signed-off-by: David Howells <dhowells@redhat.com>