BTS_Tests: make it less private and more friendly

These definitions will be also used in 'BTS_Tests_VAMOS' module.

Change-Id: Ia4eae7f14228e72cd63bd8f84e27606ac972006c
Related: SYS#4895, OS#4941
diff --git a/bts/BTS_Tests.ttcn b/bts/BTS_Tests.ttcn
index 9289673..6c5663a 100644
--- a/bts/BTS_Tests.ttcn
+++ b/bts/BTS_Tests.ttcn
@@ -294,7 +294,7 @@
 };
 
 /* Test-specific parameters */
-private type union TestSpecUnion {
+friend type union TestSpecUnion {
 	RllTestCase rll
 }
 
@@ -6209,15 +6209,15 @@
 	}
 }
 
-private type record RllTestCase {
+friend type record RllTestCase {
 	uint3_t		sapi,
 	RslLinkId	link_id,
 	octetstring	l3,
 	boolean		exp
 }
-private type record of RllTestCase RllTestCases;
-private template RllTestCase t_EITC(uint3_t sapi, RslLinkId id,
-				    octetstring l3, boolean exp) := {
+friend type record of RllTestCase RllTestCases;
+friend template RllTestCase t_EITC(uint3_t sapi, RslLinkId id,
+				   octetstring l3, boolean exp) := {
 	sapi := sapi,
 	link_id := id,
 	l3 := l3,
@@ -6350,7 +6350,7 @@
 }
 
 /* altstep to receive a LAPDm frame matching the given template */
-private altstep as_l1_exp_lapdm(template LapdmFrame exp) runs on ConnHdlr {
+friend altstep as_l1_exp_lapdm(template LapdmFrame exp) runs on ConnHdlr {
 	var L1ctlDlMessage dl;
 	[] L1CTL.receive(tr_L1CTL_DATA_IND(g_chan_nr, ?)) -> value dl {
 		var LapdmFrame lapdm;