library cleanup after a system upgrade

[Riccardo Mottola <riccardo.mottola%libero.it@localhost>]

Hi,

suppose you upgrade netbsd with a major release.
What happens to the "old libraries" ? I think they are left in so
binaries continue to run.
Just the new ones are symlinked to current.

This causes some "cruft" accumulation compared to a new install.

How can I do a cleanp?
Maybe just a find for files not symlinked or such.

I ask because I have a very tight /usr on a system for historical
partitioning reasons and it is blowing up....

Thanks,
Riccardo