math.bitwise: don't count the same bits over&over
math.bitwise: don't count the same bits over&over

slavapestov/factor,tgunr/factor,bpollack/factor,factor/factor,tgunr/factor,nicolas-p/factor,bjourne/factor,dch/factor,dch/factor,slavapestov/factor,AlexIljin/factor,slavapestov/factor,tgunr/factor,slavapestov/factor,bjourne/factor,factor/factor,slavapestov/factor,factor/factor,nicolas-p/factor,mrjbq7/factor,mrjbq7/factor,mrjbq7/factor,bjourne/factor,bpollack/factor,tgunr/factor,dch/factor,dch/factor,bpollack/factor,nicolas-p/factor,AlexIljin/factor,bpollack/factor,AlexIljin/factor,sarvex/factor-lang,mrjbq7/factor,bpollack/factor,AlexIljin/factor,slavapestov/factor,sarvex/factor-lang,bpollack/factor,tgunr/factor,nicolas-p/factor,bjourne/factor,slavapestov/factor,nicolas-p/factor,mrjbq7/factor,tgunr/factor,sarvex/factor-lang,AlexIljin/factor,dch/factor,bjourne/factor,sarvex/factor-lang,factor/factor,bjourne/factor,mrjbq7/factor,AlexIljin/factor,dch/factor,factor/factor,sarvex/factor-lang,nicolas-p/factor,sarvex/factor-lang,factor/factor,bpollack/factor,nicolas-p/factor,AlexIljin/factor,bjourne/factor,sarvex/factor-lang