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/src/libcommon/gsup_test_client.c b/src/libcommon/gsup_test_client.c
index cc0f58b..2357ba5 100644
--- a/src/libcommon/gsup_test_client.c
+++ b/src/libcommon/gsup_test_client.c
@@ -272,10 +272,11 @@
 	unsigned long long i;
 	char *server_host = "127.0.0.1";
 	uint16_t server_port = OSMO_GSUP_PORT;
+	void *ctx = talloc_named_const(NULL, 0, "gsup_test_client");
 
-	osmo_init_logging(&gsup_test_client_log_info);
+	osmo_init_logging2(ctx, &gsup_test_client_log_info);
 
-	g_gc = gsup_client_create("GSUPTEST", server_host, server_port,
+	g_gc = gsup_client_create(ctx, "GSUPTEST", server_host, server_port,
 				  gsupc_read_cb, NULL);