source upgrades by falling back to GNU ar(1) as necessary. Option
WITH_BSDAR is gone. Option _WITH_GNUAR to aid in upgrades is *not*
supposed to be set by the user.
Stop bootstrapping BSD ar(1) on the next __FreeBSD_version bump, as
there are no known bugs in it. Bump __FreeBSD_version to anticipate
this and to flag the switch to BSD ar(1), should it be needed for
something.
Input from: obrien, des, kaiw
d0ca999980