OpenSSL::Test: Avoid running IPv6 related tests if IPv6 was explicitly disabled

OpenSSL::Test: Avoid running IPv6 related tests if IPv6 was explicitly disabled

It's possible to disable IPv6  explicitly when configuring OpenSSL.  In that
case, IPv6 related tests should be skipped.

This is solved by having OpenSSL::Test::Utils::have_IPv6() check configuration
first, before trying to determine if the machine supports IPv6.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Neil Horman <nhorman@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/24748)