ctx cleanup: use non-NULL talloc ctx for osmo_init_logging2()

Fix various sanitizer complaints about memory leaks using a sanitizer build
with gcc (Debian 7.3.0-12) 7.3.0.

Also fix deprecation warnings on osmo_init_logging().

Depends: I216837780e9405fdaec8059c63d10699c695b360 (libosmocore)
Change-Id: I970c6f8a0e36a8b63e42349dbc92baff649e5cef
diff --git a/tests/gsm0408/gsm0408_test.c b/tests/gsm0408/gsm0408_test.c
index 67840f0..a934806 100644
--- a/tests/gsm0408/gsm0408_test.c
+++ b/tests/gsm0408/gsm0408_test.c
@@ -812,7 +812,9 @@
 {
 	struct gsm_network *net;
 
-	osmo_init_logging(&log_info);
+	tall_bsc_ctx = talloc_named_const(NULL, 0, "gsm0408_test");
+
+	osmo_init_logging2(tall_bsc_ctx, &log_info);
 	log_set_log_level(osmo_stderr_target, LOGL_INFO);
 
 	net = bsc_network_init(tall_bsc_ctx);