Seekdir Bug

[Matthew Dillon]

    Marc and worked out the issues and I am going to commit his fix, because
    it can't hurt, but unfortunately there is a DragonFly-specific issue
    due to our modern readdir which translate directory entries into
    a filesystem-independant form.

    And, stupid me, when I created the dirent structure I didn't add enough
    reserved fields to hold what we need, which is a full blown cookie for
    each entry.  We only have 40 bits worth of unused fields and we need
    64 bits.  I don't dare change that structure now, it would require
    every single application ever written to be recompiled.

    It may be possible to store a filename hash in the unused fields and
    then match up against the hash instead of the buffer position.  The
    problem with that though is that it would not be perfect or even close
    to perfect.

					-Matt