BUG/MINOR: unix: Don't mess up when removing the socket from the xfer_sock_list.

When removing the socket from the xfer_sock_list, we want to set
next->prev to prev, not to next->prev, which is useless.

This should be backported to 1.8.

src/proto_uxst.c

@@ -157,7 +157,7 @@ static int uxst_find_compatible_fd(struct listener *l)
 		if (xfer_sock->prev)
 			xfer_sock->prev->next = xfer_sock->next;
 		if (xfer_sock->next)
-			xfer_sock->next->prev = xfer_sock->next->prev;
+			xfer_sock->next->prev = xfer_sock->prev;
 		free(xfer_sock);
 	}
 	return ret;