VM improvements

Matthew Dillon solved a performance problem that was most noticeable when doing intensive I/O while performing other tasks; downloading a large collection of files while opening another application that read a lot of initial data, for example, would have a noticeable startup delay.  His recent VM change seems to have solved it, and the commit message has an in-depth explanation of how.

A pkgsrc project

Installation of pkgsrc packages that were built on a different version of DragonFly than the one running during that installation will cause a warning.  This can cause some confusion, since the tool appears to be warning that something may not work, but there’s no further output.  I’ve seen users think it means the install failed, for instance.

There’s potential ways around this, but the best would be this pkg_install modification suggested by Jeremy C. Reed.  Anyone who implements this gets my eternal gratitude.