doveconf: Don't read freed memory.

Giving -c parameter frees the returned orig_config_path.

src/config/doveconf.c

@@ -730,7 +730,7 @@ int main(int argc, char *argv[])
 	i_zero(&filter);
 	master_service = master_service_init("config", master_service_flags,
 					     &argc, &argv, "adf:hHm:nNpPexS");
-	orig_config_path = master_service_get_config_path(master_service);
+	orig_config_path = t_strdup(master_service_get_config_path(master_service));
 
 	i_set_failure_prefix("doveconf: ");
 	t_array_init(&module_names, 4);