libdvdread on FreeBSD

libdvdread doesn't compile correctly on FreeBSD, I think because of an 
#ifdef mistake. The following condition in dvdread/bswap.h occurs twice 
consecutively:

#elif defined(__FreeBSD__) && __FreeBSD_version >= 470000
#include <sys/endian.h>
#define B2N_16(x) x = be16toh(x)
#define B2N_32(x) x = be32toh(x)
#define B2N_64(x) x = be64toh(x)

/* This is a slow but portable implementation, it has multiple evaluation
  * problems so beware.
  * Old FreeBSD's and Solaris don't have <byteswap.h> or any other such
  * functionality!
  */

#elif defined(__FreeBSD__) && __FreeBSD_version >= 470000
#include <sys/endian.h>
#define B2N_16(x) x = (be16toh(x))
#define B2N_32(x) x = (be32toh(x))
#define B2N_64(x) \
  x = ((((x) & 0xff00000000000000) >> 56) | \
       (((x) & 0x00ff000000000000) >> 40) | \
...

I couldn't find be64toh on my 4.7-stable system, so I went with the 
second set of defines and it seems to work fine. Someone with more 
FreeBSD clue might give a better solution.

Matt