dnsdist does not compile on (k)FreeBSD

[zeha]

From the Debian buildd logs of 3.4.0-rc1:

x86_64-kfreebsd-gnu-g++ -DHAVE_CONFIG_H -I. -I..    -I/usr/include/botan-1.10    -D_FORTIFY_SOURCE=2 -I.. -I.. -DSYSCONFDIR=\"/etc/powerdns\" -DPKGLIBDIR=\"/usr/lib/x86_64-kfreebsd-gnu/pdns\" -DLOCALSTATEDIR=\"/var/run\"  -I/usr/include/lua5.1    -I../pdns/ext/rapidjson/include -I../pdns/ext/yahttp -pthread -g -O2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security -c -o dnsdist.o dnsdist.cc
[...snipped endian warnings...]
dnsdist.cc: In function 'int main(int, char**)':
dnsdist.cc:536:36: error: 'TCP_DEFER_ACCEPT' was not declared in this scope
     SSetsockopt(cs->tcpFD, SOL_TCP,TCP_DEFER_ACCEPT, 1);

[zeha]

http://cpansearch.perl.org/src/MONS/Socket-AcceptFilter-0.03/lib/Socket/AcceptFilter.pm may explain how to do a similar thing on (k)FreeBSD.