r370: The 'it does never happen -- error on close()' does happen when you exceed

r370: The 'it does never happen -- error on close()' does happen when you exceed
your quota on an AFS file system. The specific errno was thrown away by
close_normal_file(). Thus we returned NT_STATUS_UNSUCCESSFUL and not
NT_STATUS_DISK_FULL as we should. Fix that. (Not that this gives more sane
Windows app behaviour.... :-( )

Jerry, jra, could you please look over this one, it's been quite a while since
I touch file server code.

Volker
(This used to be commit 588351d1b37a900eb90eddd80882170c201e9162)