Improve performance by eliminating the fork out to swapinfo on FreeBSD which also helps prevent crashes / hangs due to the outstanding fork crash bug:
golang/go#15658
This also fixes the value reported by SwapMemory and SwapMemoryWithContext on FreeBSD which previously only included the first swap device and also reported the values in terms of 1K blocks instead of bytes.
In order to improve performance and help prevent crashes due to the outstanding fork crash bug:
https://github.com/golang/go/issues/15658
Replace string parsed values from the sysctl command with native reads of sysctl values using unix.SysctlRaw and unix.SysctlUint32.
This also merges OpenBSD and FreeBSD load implementations which are identical.
shirou