Replace NULL with nullptr

main/tests/test_astar.cpp

@@ -351,7 +351,7 @@ TestFunc test_funcs[] = {
 	test_abcx,
 	test_add_remove,
 	test_solutions,
-	NULL
+	nullptr
 };
 
 MainLoop *test() {
@@ -370,7 +370,7 @@ MainLoop *test() {
 	}
 	OS::get_singleton()->print("\n");
 	OS::get_singleton()->print("Passed %i of %i tests\n", passed, count);
-	return NULL;
+	return nullptr;
 }
 
 } // namespace TestAStar