sys/endian.h & machine/endian.h cleanup

[Joerg Sonnenberger <joerg@xxxxxxxxxxxxxxxxx>]

Hi,
the patch ftp://dragonflybsd.dyndns.org/endian.h provides a first step
to cleaning up the endian support. It is meant for inclusing after release,
but there are some show stoppers to be done first. Since the patch removes
the obsolete NTOHL family of macros, I'm going through the tree first to
clean it up.

I haven't decided wether direct mapping of htonl and ntohl to
__bswap32 for the userland will go in, because it generates a lot
of compiler warnings about long casted to __uint32_t. For the kernel
this is fine, because it denotes a possible 64-bit portability problem.

Joerg