Add a kinfo_getfile() function mimic'ing what FreeBSD's one does in libutil
Implement psutil_per_cpu_times()
Remove unused utmpx code, is only for FreeBSD >= 9
Return an empty string for psutil_proc_cwd() - there's no way to get that info.

At best you get an inode or the filesystem the process is running within..
Proper implementation for psutil_proc_open_files(), returning empty paths
enable per_cpu_times method