netinet/in.h add IPV6_MULTICAST_ALL from linux v4.20

ipv6 analogue of IP_MULTICAST_ALL sockopt.

added in linux commit 15033f0457dca569b284bef0c8d3ad55fb37eacb

include/netinet/in.h

@@ -335,6 +335,7 @@ struct ip6_mtuinfo {
 #define IPV6_V6ONLY             26
 #define IPV6_JOIN_ANYCAST       27
 #define IPV6_LEAVE_ANYCAST      28
+#define IPV6_MULTICAST_ALL      29
 #define IPV6_IPSEC_POLICY       34
 #define IPV6_XFRM_POLICY        35
 #define IPV6_HDRINCL            36