base platforms variable removal

[Kurt Hindenburg]

Hello,  from the guide and the source code, it appears that the Portfile
platforms variable is not used at all.  As such, I’m unclear why lint
says it is an error to not have it.  Regardless, if there’s no use for
it now or in the future, I could put together a PR to remove it from
base.  Then at a later time, it could be removed from Portfiles.

Regards,
 Kurt

-- 
  Kurt Hindenburg
  khindenburg at macports.org