Introduce <machine/_endian.h> to let target based customization of
<machine/endian.h> via
* _LITTLE_ENDIAN,
* _BIG_ENDIAN,
* _PDP_ENDIAN, and
* _BYTE_ORDER.
defines. Add definitions expected by FreeBSD to
<machine/endian.h> like
* _QUAD_HIGHWORD,
* _QUAD_LOWWORD,
* __bswap16(),
* __bswap32(),
* __bswap64(),
* __htonl(),
* __htons(),
* __ntohl(), and
* __ntohs().
Also, if __BSD_VISIBLE
* LITTLE_ENDIAN,
* BIG_ENDIAN,
* PDP_ENDIAN, and
* BYTE_ORDER.
Targets that define __machine_host_to_from_network_defined in
<machine/_endian.h> must provide their own implementation of
* __htonl(),
* __htons(),
* __ntohl(), and
* __ntohs(),
otherwise a default implementation is provided by <machine/endian.h>.
In case of GCC defines to builtins are used.
Signed-off-by: Sebastian Huber <sebastian.huber@embedded-brains.de>