The program attempts to obtain the identification and capabilities
of the currently used CPU, and print the matching set of CPU_FLAGS_*
flags for Gentoo Linux, but it could be useful for FreeBSD as well.

The output format is compatible both with Portage (package.use) and
Paludis (use.conf/options.conf).

On x86 platforms, the program issues the CPUID instruction to obtain
processor capabilities.

On ARM platforms, the userspace processes are not allowed to obtain
processor information directly.  Instead, the program is relying on
kernel identification of the CPU provided via the system interfaces.