In soreceive_generic() when checking if the type of mbuf has changed

check it for MT_CONTROL type too, otherwise the assertion
"m->m_type == MT_DATA" below may be triggered by the following scenario:

- the sender sends some data (MT_DATA) and then a file descriptor
  (MT_CONTROL);
- the receiver calls recv(2) with a MSG_WAITALL asking for data larger
  than the receive buffer (uio_resid > hiwat).

MFC after:	2 week

sys/kern/uipc_socket.c

@@ -1695,8 +1695,8 @@ dontblock:
 		 * examined ('type'), end the receive operation.
 	 	 */
 		SOCKBUF_LOCK_ASSERT(&so->so_rcv);
-		if (m->m_type == MT_OOBDATA) {
-			if (type != MT_OOBDATA)
+		if (m->m_type == MT_OOBDATA || m->m_type == MT_CONTROL) {
+			if (type != m->m_type)
 				break;
 		} else if (type == MT_OOBDATA)
 			break;