task #13907: PPP cleanups: Move PPP mempools out of lwIP core to PPP code

src/include/netif/ppp/ppp_impl.h

@@ -378,6 +378,13 @@ struct pppd_stats {
  * PPP private functions
  */
 
+ 
+/*
+ * Functions called from lwIP core.
+ */
+
+/* initialize the PPP subsystem */
+int ppp_init(void);
 
 /*
  * Functions called from PPP link protocols.