BTS_Test_ASCI: Add UPLINK FREE / UPLINK BUSY test

A VGCS channel is activated. The BSC sends UPLINK FREE message and
UPLINK BUSY message. When the UPLINK FREE message is sent, the MS is
expected to receive several UPLINK FREE messages. Then the UPLINK BUSY
message is sent, the MS is expected to receive one UPLINK BUSY message.

Change-Id: I2f70adb4a6f71eb8972feccf9dda0f77e7a942b9
Related: OS#4851
diff --git a/bts/BTS_Tests.ttcn b/bts/BTS_Tests.ttcn
index d893601..d92b9c6 100644
--- a/bts/BTS_Tests.ttcn
+++ b/bts/BTS_Tests.ttcn
@@ -2501,7 +2501,7 @@
 }
 
 /* Tune to a dedicated channel: L1CTL only */
-private function f_l1ctl_est_dchan(L1CTL_PT pt, ConnHdlrPars pars) {
+friend function f_l1ctl_est_dchan(L1CTL_PT pt, ConnHdlrPars pars) {
 	if (not pars.fhp.enabled) {
 		var TrxParsItem trx_pars := mp_trx_pars[pars.trx_nr];
 		pt.send(ts_L1CTL_DM_EST_REQ_H0(pars.chan_nr, pars.tsc,
@@ -7338,7 +7338,7 @@
 		}
 	[] L1CTL.receive { repeat; }
 }
-private function f_l1_exp_lapdm(template LapdmFrame exp, float t := 3.0) runs on ConnHdlr {
+friend function f_l1_exp_lapdm(template LapdmFrame exp, float t := 3.0) runs on ConnHdlr {
 	timer T := t;
 	T.start;
 	alt {