That's good, is it running fine on FreeBSD?

I committed the changes to headers.h.  For consistency, I used __BSD__.  The complete list of defines is at http://docs.wxwidgets.org/stable/wx_cppconst.html
#ifdef __BSD__
#include <netinet/in.h>
#endif

malloc.h is only needed on windows, I'll move that into the __WXMSW__ section before it causes any more trouble.