Use G_OPTION_ENTRY_NULL to avoid missing initializer warnings

gio/glib-compile-resources.c

@@ -747,7 +747,7 @@ main (int argc, char **argv)
     { "internal", 0, 0, G_OPTION_ARG_NONE, &internal, N_("Don’t export functions; declare them G_GNUC_INTERNAL"), NULL },
     { "external-data", 0, 0, G_OPTION_ARG_NONE, &external_data, N_("Don’t embed resource data in the C file; assume it's linked externally instead"), NULL },
     { "c-name", 0, 0, G_OPTION_ARG_STRING, &c_name, N_("C identifier name used for the generated source code"), NULL },
-    { NULL }
+    G_OPTION_ENTRY_NULL
   };
 
 #ifdef G_OS_WIN32