There was a logic mistake, so the limit in question wasn't used. On my
macOS this doesn't seem to matter, the hard limit returned is 2^63-1 and
setting the soft limit to that works. However I'm assuming that's not
the case for older macOSes since it was so nicely documented, so we
should still have this working. (10240 FDs should be enough for
anybody.)
This will decrease the risk of running out of file descriptors for the
database and other bad things, which could otherwise potentially happen
if we're serving lots of requests and scanning in parallel, etc.
Windows doesn't have a per process open file limit like Unix so we don't
need to worry about it there.
