HAL ported to FreeBSD

[Artem Kachitchkine]

>     I like the ideal of having a shared script, e.g.
>     hal-system-lcd-get-brightness that is shared between
>     OS'es because we will do the policy checking in it. Maybe the
>     answer here is to have 
> 
>      tools/linux/hal-system-lcd-get-brightness-linux
>      tools/freebsd/hal-system-lcd-get-brightness-freebsd
>      tools/solaris/hal-system-lcd-get-brightness-solaris
> 
>     and have tools/hal-system-lcd-get-brightness call the right one.
>     Then on e.g. FreeBSD you don't have to install the bits in 
>     tools/linux or tools/solaris. Is this cool with you? Artem, what
>     do you think?

That sounds good to me. At least with the right makefile infrastructure 
under 'tools' (similar to what we have under 'hald' for backends) we can 
choose the right level of sharing for each component.

-Artem.