Boost

[nia <nia%NetBSD.org@localhost>]

I think there's a strong argument for the boost packages
to be versioned - currently so much breaks every time a new version
is released, and someone's toes get stepped on.

Clearly there are people that want the newest version, but I can't
stand repeatedly patching the same software every time a boost update
is committed.

Installing each boost version to its own isolated directories,
then using BUILDLINK_INCDIRS/BUILDLINK_LIBDIRS to ensure the
correct version gets selected seems the best way to end this
cycle.

IMO, the boost version should be frozen as it stands currently,
and any update should be committed to a new package directory.

Most others seem to have had the same idea:

https://repology.org/project/boost/versions