RAM optimizations

Trying to save RAM wherever possible for Ublox C027 platform

features/FEATURE_LWIP/lwip-interface/lwip/src/netif/ppp/lwip_utils.c

@@ -605,7 +605,11 @@ 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) {
+#ifdef PPP_LOGIT_BUFSIZE
+    char buf[PPP_LOGIT_BUFSIZE];
+#else
     char buf[1024];
+#endif
 
     ppp_vslprintf(buf, sizeof(buf), fmt, args);
     ppp_log_write(level, buf);

features/FEATURE_LWIP/lwip-interface/lwipopts.h

@@ -265,6 +265,7 @@
 // Save RAM
 #define PAP_SUPPORT                 0
 #define VJ_SUPPORT                  0
+#define PPP_LOGIT_BUFSIZE           512
 
 //Hate the config hassle.
 //#define LWIP_USE_EXTERNAL_MBEDTLS       1
@@ -288,6 +289,9 @@
 #define LWIP_NETIF_STATUS_CALLBACK  1
 #define LWIP_NETIF_LINK_CALLBACK    1
 
+#define DNS_TABLE_SIZE                  2
+#define DNS_MAX_NAME_LENGTH             128
+
 #include <lwip/arch.h>
 #include "lwip_random.h"
 #include "lwip_tcp_isn.h"