fix(arch): obsolete ipv6 define
fix(arch): obsolete ipv6 define

According to Linux /usr/include/bits/in.h IPV6_ADD_MEMBERSHIP is
obsolete.  It does not exist on OpenBSD.  Use IPV6_JOIN_GROUP
instead.

open62541/open62541,jpfr/open62541,jpfr/open62541,JGrothoff/open62541,open62541/open62541,jpfr/open62541,JGrothoff/open62541,jpfr/open62541,open62541/open62541,JGrothoff/open62541,JGrothoff/open62541,open62541/open62541