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/gtphub/gtphub_test.c b/tests/gtphub/gtphub_test.c
index ac0223b..2e48bb1 100644
--- a/tests/gtphub/gtphub_test.c
+++ b/tests/gtphub/gtphub_test.c
@@ -1762,8 +1762,9 @@
 
 int main(int argc, char **argv)
 {
-	osmo_init_logging(&info);
 	osmo_gtphub_ctx = talloc_named_const(NULL, 0, "osmo_gtphub");
+	void *log_ctx = talloc_named_const(osmo_gtphub_ctx, 0, "log");
+	osmo_init_logging2(log_ctx, &info);
 
 	test_nr_map_basic();
 	test_nr_map_wrap();
@@ -1780,7 +1781,9 @@
 	printf("Done\n");
 
 	talloc_report_full(osmo_gtphub_ctx, stderr);
+	talloc_free(log_ctx);
 	OSMO_ASSERT(talloc_total_blocks(osmo_gtphub_ctx) == 1);
+	talloc_free(osmo_gtphub_ctx);
 	return 0;
 }