cpumask_t/cpuset_t changes in CURRENT and non-base gcc

I think that if you use non-base gcc for ports on CURRENT, then you need to follow
this procedure after upgrading world to a revision after the cpumask_t/cpuset_t
change:
1. upgrade/re-install gccXX using base gcc as a bootstrap compiler (make CC=gcc)
2. everything else... :)

-- 
Andriy Gapon