reenable ARP queuing in lwIP2 by courtesy of @aboulfad

esp8266#3481 (comment)

Author: d-a-v

tools/sdk/lib/liblwip2-1460-feat.a

@@ -1,5 +1,5 @@
 // generated by makefiles/make-lwip2-hash
 #ifndef LWIP_HASH_H
 #define LWIP_HASH_H
-#define LWIP_HASH_STR "STABLE-2_1_2_RELEASE/glue:1.1-5-g25d5e81"
+#define LWIP_HASH_STR "STABLE-2_1_2_RELEASE/glue:1.1-7-g82abda3"
 #endif // LWIP_HASH_H

tools/sdk/lib/liblwip2-1460.a

@@ -660,7 +660,7 @@
  * packet in a row to an IP address that is not in the ARP cache.
  */
 #if !defined ARP_QUEUEING || defined __DOXYGEN__
-#define ARP_QUEUEING                    0
+#define ARP_QUEUEING                    1
 #endif
 
 /** The maximum number of packets which may be queued for each