ttcn3: Allow remote hosts (sysmobts) to access RSL srv inside TTCN3 docker

And extra IP address is required/requested on the docker host because
the BSC handling the OML instance is binding to it's address, so we
cannot ask docker to use that one because it fails binding to it.

Change-Id: I734fba91db535d7b183ddc7f51d324a6cd2eaf6f
diff --git a/ttcn3/suites/ttcn3_bts_tests/ttcn3_bts_tests.py b/ttcn3/suites/ttcn3_bts_tests/ttcn3_bts_tests.py
index f36b023..2684bf7 100755
--- a/ttcn3/suites/ttcn3_bts_tests/ttcn3_bts_tests.py
+++ b/ttcn3/suites/ttcn3_bts_tests/ttcn3_bts_tests.py
@@ -30,7 +30,8 @@
 msc_dummy.start()
 mgw_dummy.start()
 
-bsc.set_rsl_ip('172.18.9.10')
+nat_rsl_ip = suite.ip_address().get('addr')
+bsc.set_rsl_ip(nat_rsl_ip)
 bsc.bts_add(bts)
 sgsn_dummy.bts_add(bts)
 
@@ -52,7 +53,7 @@
 else: # PCU unix socket not available locally
     pcu_available = False
     pcu_sk = ''
-docker_cmd = (script_file, str(script_run_dir), junit_ttcn3_dst_file, osmocon.l2_socket_path(), pcu_sk)
+docker_cmd = (script_file, str(script_run_dir), junit_ttcn3_dst_file, nat_rsl_ip, osmocon.l2_socket_path(), pcu_sk)
 
 print('Creating template')
 mytemplate = Template(filename=bts_tmpl_file)