basic: Add our own <netinet/in.h> and <net/if.h> headers

These glibc headers conflicts with the corresponding linux headers
(<linux/in.h> and <linux/if.h>) and impose an include order (the glibc one
has to be included before any linux header is included). This makes sorting
includes a royal pain so let's define our own versions of these headers using
various linux headers to do all the work and filling in the missing bits
ourselves.

src/resolve/resolved-dns-scope.c

@@ -929,7 +929,7 @@ static int dns_scope_multicast_membership(DnsScope *s, bool b, struct in_addr in
         } else if (s->family == AF_INET6) {
                 struct ipv6_mreq mreq = {
                         .ipv6mr_multiaddr = in6,
-                        .ipv6mr_interface = s->link->ifindex,
+                        .ipv6mr_ifindex = s->link->ifindex,
                 };
 
                 if (s->protocol == DNS_PROTOCOL_LLMNR)