virt-admin: Fix segfault when libvirtd dies

vshAdmCatchDisconnect requires non-NULL structure vshControl for
getting connection name (stored at opaque), but
virAdmConnectRegisterCloseCallback at vshAdmConnect called it
with NULL.

Signed-off-by: Adam Julis <ajulis@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Ján Tomko <jtomko@redhat.com>

tools/virt-admin.c

@@ -112,7 +112,7 @@ vshAdmConnect(vshControl *ctl, unsigned int flags)
         return -1;
     } else {
         if (virAdmConnectRegisterCloseCallback(priv->conn, vshAdmCatchDisconnect,
-                                               NULL, NULL) < 0)
+                                               ctl, NULL) < 0)
             vshError(ctl, "%s", _("Unable to register disconnect callback"));
 
         if (priv->wantReconnect)