gmake config.guess

[Justin Cormack <justin%specialbusservice.com@localhost>]

Trying to do a cross build on Linux mips64 and the gmake config.guess
doesn't recognise this architecture (it is from 2002!). The one from
gmake 3.81 is fine (its four years later); thats the last GPL2
release, so perhaps it would be possible to update that file? (Is
there any reason we did not update to gmake 3.81 anyway?).

Justin