gaih_inet: Split nscd lookup code into its own function.

Add a new member got_ipv6 to indicate if the results have an IPv6
result and use it instead of the local got_ipv6.

Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Reviewed-by: DJ Delorie <dj@redhat.com>
(cherry picked from commit e7e5315b)