Remove ability to compile without IPv6 support.

This was the source of a large number of #ifdefs, originally
included for use with old embedded libc versions. I'm
sure no-one wants or needs IPv6-free code these days, so this
is a move towards more maintainable code.

src/edns0.c

@@ -301,20 +301,14 @@ static size_t add_mac(struct dns_header *header, size_t plen, unsigned char *lim
 
 struct subnet_opt {
   u16 family;
-  u8 source_netmask, scope_netmask;
-#ifdef HAVE_IPV6 
+  u8 source_netmask, scope_netmask; 
   u8 addr[IN6ADDRSZ];
-#else
-  u8 addr[INADDRSZ];
-#endif
 };
 
 static void *get_addrp(union mysockaddr *addr, const short family) 
 {
-#ifdef HAVE_IPV6
   if (family == AF_INET6)
     return &addr->in6.sin6_addr;
-#endif
 
   return &addr->in.sin_addr;
 }
@@ -330,7 +324,6 @@ static size_t calc_subnet_opt(struct subnet_opt *opt, union mysockaddr *source)
   opt->source_netmask = 0;
   opt->scope_netmask = 0;
 
-#ifdef HAVE_IPV6
   if (source->sa.sa_family == AF_INET6 && daemon->add_subnet6)
     {
       opt->source_netmask = daemon->add_subnet6->mask;
@@ -342,7 +335,6 @@ static size_t calc_subnet_opt(struct subnet_opt *opt, union mysockaddr *source)
       else 
 	addrp = &source->in6.sin6_addr;
     }
-#endif
 
   if (source->sa.sa_family == AF_INET && daemon->add_subnet4)
     {
@@ -356,11 +348,7 @@ static size_t calc_subnet_opt(struct subnet_opt *opt, union mysockaddr *source)
 	  addrp = &source->in.sin_addr;
     }
   
-#ifdef HAVE_IPV6
   opt->family = htons(sa_family == AF_INET6 ? 2 : 1);
-#else
-  opt->family = htons(1);
-#endif
   
   len = 0;