use osmo_init_logging2(), fix regression test memleaks

Particularly gbproxy_test.c had various mem leaks, which (will) show up with
gcc (Debian 7.3.0-15) 7.3.0 address sanitizer. Fix those leaks to verify that
we don't have memleaks in the production code.

Change-Id: Ia4204c8b3d895b42c103edecb61b99d3d22bd36f
diff --git a/tests/sgsn/sgsn_test.c b/tests/sgsn/sgsn_test.c
index 2fbd6e4..df4df3b 100644
--- a/tests/sgsn/sgsn_test.c
+++ b/tests/sgsn/sgsn_test.c
@@ -2444,8 +2444,8 @@
 	void *osmo_sgsn_ctx;
 	void *msgb_ctx;
 
-	osmo_init_logging(&info);
 	osmo_sgsn_ctx = talloc_named_const(NULL, 0, "osmo_sgsn");
+	osmo_init_logging2(osmo_sgsn_ctx, &info);
 	tall_bsc_ctx = talloc_named_const(osmo_sgsn_ctx, 0, "bsc");
 	msgb_ctx = msgb_talloc_ctx_init(osmo_sgsn_ctx, 0);