* you can #include <sys/endian.h> instead of <machine/endian.h>,
and ditto <endian.h>  (fixes code that pulls in <sys/endian.h> first)
* those will always export the symbols that POSIX specified for
<endian.h>, including the new {be,le}{16,32,64}toh() set.  c.f.
http://austingroupbugs.net/view.php?id=162
if __BSD_VISIBLE then you also get the symbols that our <machine/endian.h>
currently exports (ntohs, NTOHS, dlg's bemtoh*, etc)
* when doing POSIX compiles (not __BSD_VISIBLE), then <netinet/in.h> and
<arpa/inet.h> will *stop* exporting the extra symbols like BYTE_ORDER
and betoh*
ok deraadt@