Prefer pageing to swapping

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

Hi,

I notice that ftp.netbsd.org is swapping even when not paging. This patch
changes the pagedaemon to prefer paging to swapping, and ups the minimum
free limit.

        http://www.netbsd.org/~ad/pdaemon.diff

Comments?

Thanks,
Andrew