Changed the "resolve" test precheck program to verify that an IPv6 socket

can be created before resolving the IPv6 name.  In the context of running
a test, it doesn't make sense to run an IPv6 test when a host is resolvable
but IPv6 isn't usable.  This should fix failures of test 1085 on hosts with
library and DNS support for IPv6 but where actual use of IPv6 has been
administratively disabled.