Heads up: descriptor/kqueue changes

[Andrew Doran <ad%netbsd.org@localhost>]

Hi,

I just rototilled the file descriptor and kqueue code (4.99.56). While the
changes fix a lot of bugs, it's possible that new ones have been introduced.
Given the scope of the changes I haven't been able to test everything that
has changed, so: just a heads up.

Thanks,
Andrew