[OE-core] Add recipe for hplip 3.12.6

[Marc Reilly]

Hi,

> > This is based on a recipe for an earlier version which didn't seem to
> > make it into oe-core. I'm guessing that oe-core is the correct place for
it:
> > next to cups, ghostscript and foomatic.
> 
> Since this is something that not everyone needs I think the best place for
it is
> probably meta-oe. I believe the justification for having cups etc.
available in
> OE-Core is that these are required when you want LSB compliance.

Fair enough, I'll respin it for meta-oe.

Cheers,
Mare