-stable machine via the old-school methods):
Use __FreeBSD_version in preference to __FreeBSD__ >= N where possible.
Define a single variable mythread which is set to curproc or curthread
depending on the OS version (with a comment saying it is a white lie on
4.x since it really is a proc).
NB: __FreeBSD__ is the OS level of the host machine, not the target,
and should never be used, if possible, as __FreeBSD__ >= N.
3e109d2cd3