util: include the target address in socket connect failures

Reporting "Failed to connect socket" is essentially useless for a user
attempting to diagnose failure. It needs to include the target address
details. Similarly when failing to create a socket we should include the
socket family info, so the user understands what particular feature was
missing in their kernel build (IPv6, VSock in particular).

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>