bts: Stop all components before mtc.stop in f_shutdown

This is the bts version of patch 637ef6c8

Again I picked a test that sometimes failed -
BTS_Tests.TC_sacch_info_mod - and ran it 20 times before and after this
commit. Before it failed roughly half the time with a DTE and after I
was not able to make it fail.

Change-Id: I96f02037283b79a93ef4d659b00a90ac519c0a75
diff --git a/bts/BTS_Tests.ttcn b/bts/BTS_Tests.ttcn
index 04c4043..40bfd24 100644
--- a/bts/BTS_Tests.ttcn
+++ b/bts/BTS_Tests.ttcn
@@ -342,6 +342,7 @@
 
 function f_shutdown() runs on test_CT {
 	/* mtc.stop cleanly stops testcase execution to avoid unclean shutdown */
+	all component.stop;
 	mtc.stop;
 }