tests/socket-helpers: Treat EAI_NONAME as EADDRNOTAVAIL

tests/socket-helpers: Treat EAI_NONAME as EADDRNOTAVAIL

The tests/test-char test is currently always failing on my system since
the getaddrinfo() in socket_can_bind_connect() returns EAI_NONAME when
it is called from socket_check_protocol_support() to check for IPv6.
socket_check_protocol_support() then returns -1 and thus the tests are
not run at all - even though IPv4 is working fine.
socket_can_bind_connect() connect should return EADDRNOTAVAIL in this
case instead, so that socket_check_protocol_support() does not fail.

Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200908121543.222872-1-thuth@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>