add new IPV6_AUTOFLOWLABEL socket option in netinet/in.h

added in linux v3.17 commit 753a2ad54ef45e3417a9d49537c2b42b04a2e1be
enables automatic flow label generation on transmit

include/netinet/in.h

@@ -358,6 +358,7 @@ struct ip6_mtuinfo
 #define IPV6_DONTFRAG           62
 #define IPV6_RECVTCLASS         66
 #define IPV6_TCLASS             67
+#define IPV6_AUTOFLOWLABEL      70
 #define IPV6_ADDR_PREFERENCES   72
 #define IPV6_MINHOPCOUNT        73
 #define IPV6_ORIGDSTADDR        74