_nettle_write_be32

[Nikos Mavrogiannopoulos]

Hello,
 Would it be possible to export _nettle_write_be32? It is a useful
function and can be used on the accelerated versions of SHA in
architectures that support it (i.e. VIA cpus). I currently include a
copy of it, but would be nice if it was exported from the nettle API as
well.

btw. the MD_* macros were also proved to be very useful in that case.

regards,
Nikos