tipc_get_gap_ack_blks
glen = tipc_get_gap_ack_blks(&ga, l, hdr, false);
glen = tipc_get_gap_ack_blks(&ga, l, hdr, true);
u16 tipc_get_gap_ack_blks(struct tipc_gap_ack_blks **ga, struct tipc_link *l,