library/RTP_Emulation: improve readability of guard statements

Change-Id: Ic25646cca5c276feae8dda52153991a8d16913e1
diff --git a/library/RTP_Emulation.ttcn b/library/RTP_Emulation.ttcn
index 900a196..728d352 100644
--- a/library/RTP_Emulation.ttcn
+++ b/library/RTP_Emulation.ttcn
@@ -493,10 +493,10 @@
 
 
 		/* simply ignore any RTTP/RTP if receiver not enabled */
-		[g_rx_enabled==false] RTP.receive(tr_rtp) {
+		[not g_rx_enabled] RTP.receive(tr_rtp) {
 			g_stats_rtp.num_pkts_rx_err_disabled := g_stats_rtp.num_pkts_rx_err_disabled+1;
 			}
-		[g_rx_enabled==false] RTCP.receive(tr_rtcp) {
+		[not g_rx_enabled] RTCP.receive(tr_rtcp) {
 			g_stats_rtcp.num_pkts_rx_err_disabled := g_stats_rtcp.num_pkts_rx_err_disabled+1;
 			}