Build on the change in revision 1.98 by Tor.Egge@fast.no.

Build on the change in revision 1.98 by Tor.Egge@fast.no.
The symptom being treated in 1.98 was to avoid freeing a
pagedep dependency if there was still a newdirblk dependency
referencing it. That change is correct and no longer prints
a warning message when it occurs. The other part of revision
1.98 was to panic when a newdirblk dependency was encountered
during a file truncation. This fix removes that panic and
replaces it with code to find and delete the newdirblk
dependency so that the truncation can succeed.