iked: introduce and use print_addr()

iked: introduce and use print_addr()

The vast majority of print_host() callers cast the first argument
(usually a sockaddr_storage *) to (struct sockaddr *) and pass both
a NULL buffer and 0 length. Cast and useless arguments lead to
awkward line wrapping in many places. Clean this up by introducing a
helper. Make this helper take a void pointer, so all casts go away.

ok claudio kn tobhe