HP-UX only returns IPv6 addresses using SIOCGLIFCONF,
SIOCGIFCONF has to be used for IPv4 addresses.
Solaris uses the same code as described in the comments, which
should correctly detect all addresses when running in a zone.
This adds the code that went missing from commit e20183da.
Signed-off-by: Love Hornquist Astrand <lha@h5l.org>