make buildworld failure

[R. E. Ceiver]

    I'm still fairly certain that this is a /var/tmp issue.
You're right. It obviously was, but I'm not really sure why. I had 
mounted /tmp as MFS and /var/tmp linked to /tmp. Now as I unmounted 
/tmp and compiled anew, everything went alright.

Since a make buildworld takes about 12 hours on that Compaq lightning, 
I will try to reproduce it the next time a significant codebase change 
happens.

Thanks for the hint
--markus