msc_vlr_tests: make all test functions static

All functions in the individual msc_vlr_test_*.c files should be static; hence
we would be warned if one of them were unused (forgotten to add to the tests
array).

Change-Id: Ia169c6a1443a48879ab4777e09c2040c48810bf6
diff --git a/tests/msc_vlr/msc_vlr_test_ms_timeout.c b/tests/msc_vlr/msc_vlr_test_ms_timeout.c
index 4cfd035..c81f5b5 100644
--- a/tests/msc_vlr/msc_vlr_test_ms_timeout.c
+++ b/tests/msc_vlr/msc_vlr_test_ms_timeout.c
@@ -23,7 +23,7 @@
 
 #include "msc_vlr_tests.h"
 
-void test_ms_timeout_lu_auth_resp()
+static void test_ms_timeout_lu_auth_resp()
 {
 	comment_start();
 
@@ -83,7 +83,7 @@
 	comment_end();
 }
 
-void test_ms_timeout_cm_auth_resp()
+static void test_ms_timeout_cm_auth_resp()
 {
 	comment_start();
 
@@ -182,7 +182,7 @@
 	comment_end();
 }
 
-void test_ms_timeout_paging()
+static void test_ms_timeout_paging()
 {
 	struct vlr_subscr *vsub;
 	const char *imsi = "901700000004620";