factor.sh: require high enough version of clang/gcc. Fixes #1440.
factor.sh: require high enough version of clang/gcc. Fixes #1440.

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