Expire not doing much

[Marc Newman <mknewman@blkbox.com>]

Expire does seem to be running, but not removing anything (or much).  Once
the partition fills up (it shouldn't get that high, I have 4,000,000
blocks free specified in the nntpcache.config) it hovers around 500 blocks
free and is almost continually expiring.

Solaris X86 2.5.1, gcc, latest nntpcache.

Thanks,
Marc