AF_VSOCK connection refused errno

When connect(2) fails because the peer is not listening the virtio vsock
transport returns ECONNRESET.  I believe the VMCI transport does the
same (based on code inspection).

Jorgen: Can you confirm this VMCI transport behavior?

I'd like to change to ECONNREFUSED for all transports because developers
will be surprised when they get ECONNRESET.  It makes porting AF_INET
code harder.

On the other hand, it may be too late to fix this if there userspace
applications that rely on ECONNRESET?  I'm not aware of any such
applications myself.

Thanks,
Stefan