socket-util: filter out VMADDR_CID_ANY in vsock_get_local_cid()

It has been observed on some systems[1] that ssh-issue may print out:

 Try contacting this VM's SSH server via 'ssh vsock%4294967295' from host.

i.e. it suggests connecting with VMADDR_CID_ANY, which is not valid. It
seems that IOCTL_VM_SOCKETS_GET_LOCAL_CID may return VMADDR_CID_ANY in
some cases, e.g. when vsock is not full initialized or so.

Treat VMADDR_CID_ANY as special in vsock_get_local_cid(), the same as
VMADDR_CID_LOCAL and VMADDR_CID_HOST, and return an error.

[1] https://launchpad.net/bugs/2145027

src/basic/socket-util.c

@@ -1794,7 +1794,7 @@ int vsock_get_local_cid(unsigned *ret) {
         /* If ret == NULL, we're just want to check if AF_VSOCK is available, so accept
          * any address. Otherwise, filter out special addresses that are cannot be used
          * to identify _this_ machine from the outside. */
-        if (ret && IN_SET(tmp, VMADDR_CID_LOCAL, VMADDR_CID_HOST))
+        if (ret && IN_SET(tmp, VMADDR_CID_LOCAL, VMADDR_CID_HOST, VMADDR_CID_ANY))
                 return log_debug_errno(SYNTHETIC_ERRNO(EADDRNOTAVAIL),
                                        "IOCTL_VM_SOCKETS_GET_LOCAL_CID returned special value (%u), ignoring.", tmp);