WIP: quic: Add a BUG_ON to qc_send()

This is to ensure qc_send() respects the <max_dgrams> limit passed
as parameter.

src/quic_tx.c

@@ -880,6 +880,7 @@ int qc_send(struct quic_conn *qc, int old_data, struct list *send_list,
 		}
 
 		ret += prep_pkts;
+		BUG_ON(max_dgrams && ret > max_dgrams);
 		if (max_dgrams && ret == max_dgrams && !LIST_ISEMPTY(send_list)) {
 			TRACE_DEVEL("stopping for artificial pacing", QUIC_EV_CONN_TXPKT, qc);
 			break;