lwip2 fixes: turn off random delay before sntp request (#5567)

+update dhcp6 patch: update ip_addr_set_zero_ip6 to use IP_SET_TYPE_VAL, avoiding compilation warning

tools/sdk/lwip2/include/lwip-git-hash.h

@@ -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:1.0-6-g4670dfc"
+#define LWIP_HASH_STR "STABLE-2_1_2_RELEASE/glue:1.0-9-g56e0410"
 #endif // LWIP_HASH_H

tools/sdk/lwip2/include/lwip/ip_addr.h

@@ -169,7 +169,7 @@ extern const ip_addr_t ip_addr_any_type;
   ip6_addr_set_zero(ip_2_ip6(ipaddr)); IP_SET_TYPE(ipaddr, IPADDR_TYPE_V4); }while(0)
 /** @ingroup ip6addr */
 #define ip_addr_set_zero_ip6(ipaddr)     do{ \
-  ip6_addr_set_zero(ip_2_ip6(ipaddr)); IP_SET_TYPE(ipaddr, IPADDR_TYPE_V6); }while(0)
+  ip6_addr_set_zero(ip_2_ip6(ipaddr)); IP_SET_TYPE_VAL(*ipaddr, IPADDR_TYPE_V6); }while(0)
 /** @ingroup ipaddr */
 #define ip_addr_set_any(is_ipv6, ipaddr)      do{if(is_ipv6){ \
   ip6_addr_set_any(ip_2_ip6(ipaddr)); IP_SET_TYPE(ipaddr, IPADDR_TYPE_V6); }else{ \

tools/sdk/lwip2/include/lwipopts.h

@@ -3555,6 +3555,17 @@
 #define SNTP_MAX_SERVERS                3
 #endif
 
+// turn off random delay before sntp request
+// when SNTP_STARTUP_DELAY is not defined,
+// LWIP_RAND is used to set a delay
+// from sntp_opts.h:
+/** According to the RFC, this shall be a random delay
+ * between 1 and 5 minutes (in milliseconds) to prevent load peaks.
+ * This can be defined to a random generation function,
+ * which must return the delay in milliseconds as u32_t.
+ */
+#define SNTP_STARTUP_DELAY              0
+
 /*
    --------------------------------------------------
    ------------------- LOCAL FIXES ------------------