Patches for Hurd and FreeBSD

[Jeremie Koenig]

Hello,

These patches add Hurd and FreeBSD support to BusyBox. The approach of
tagging Linux-only configuration options as depending on PLATFORM_LINUX
has been taken.  The subsequent patches fix portability problems in some
applets and remove this dependency as a result.

These patches have already been committed (daf286c..2ea12d8);
I initially screwed up and sent them to Denys only (sorry about that).
Please feel free to comment on any problem you may see and I'll try to
deal with them.

The rest of my series (to be fixed and re-submitted) will be coming soon.

Thanks,
-- 
Jeremie Koenig <jk at jk.fr.eu.org>