Even thought OpenBSD often breaks the ABI compatibility and doesn't make
*any* promise of "stability", this project aims to be "pure go" so avoid
doing inter-op at the cost of artificially reducing the number of
supported architectures down to amd64 and i386.
To add support for another architecture (e.g. arm), add another file
cpu_openbsd_${arch}.go like done for 386 and amd64. The fields are
declared as `long' in C, so pick the appropriate size when declaring the
struct.
