truncated directory for some NFS servers. This turned out to
be because the size of a directory reported by an NFS server
can be smaller that the ufs-like directory created from the
RPC XDR in the client. This patch fixes the problem by changing
r248567 so that vnode_pager_setsize() is only done for regular files.
Reported and tested by: hartmut.brandt@dlr.de
Reviewed by: kib
MFC after: 1 week