LWIP 2.1.2 tcpip thread stack overflow fix.

Applied missing LWIP patch to PPP/utils.c
"Major Refactoring & extensions" commited on May 23, 201 by hasnainvirk
LWIP 2.1.2 tcpip thread stack is restored to 1200 bytes

Author: tymoteuszblochmobica

features/lwipstack/lwip/src/netif/ppp/lwip_utils.c

@@ -603,7 +603,7 @@ void ppp_print_string(const u_char *p, int len, void (*printer) (void *, const c
  * ppp_logit - does the hard work for fatal et al.
  */
 static void ppp_logit(int level, const char *fmt, va_list args) {
-    char buf[1024];
+    char buf[256];
 
     ppp_vslprintf(buf, sizeof(buf), fmt, args);
     ppp_log_write(level, buf);