FreeBSD, like OpenBSD, uses BIG_ENDIAN, LITTLE_ENDIAN, and BYTE_ORDER,
whereas Linux and compatibles use __-prefixed names. Define the names
the same as the OpenBSD block below it.
#endif
#ifdef __FreeBSD__
# include <sys/endian.h> /* htole32 and friends */
+# define __BYTE_ORDER BYTE_ORDER
+# define __LITTLE_ENDIAN LITTLE_ENDIAN
+# define __BIG_ENDIAN BIG_ENDIAN
#elif defined(__OpenBSD__)
# include <endian.h>
# define __BYTE_ORDER BYTE_ORDER