vos: Restore some VNOVOL error messages

Many places in vos/vsprocs have code to delete a volume. Commit
f4e73067cdef990262c69c38ac98761620a63f25 tried to refactor them by
consolidating the common "delete" code into DoVolDelete. However, not
all of the removed code had exactly the same behavior, and some of
these variants were not handled by DoVolDelete.

One such variation is that DoVolDelete always printed an error message
if the target volume did not exist. But for some call sites this
condition is not an error, and prior to the refactoring they did not
print such an error message. Commit
1092cbe34fc8519826b3fa0565505b7bd81bc922 tried to correct this by
suppressing the error message if the target volume does not exist.
However, this means that all DoVolDelete calls do not print such an
error, where some should and some should not print an error. This
means that in some edge cases when we encounter an unexpected VNOVOL
error, we now skip printing the specific error we got and instead go
right to cleanup/recovery/exit. For a few other cases, we used to
print an error and continue (because it is a non-fatal error or a
warning), but now we print nothing when we encounter a VNOVOL error.

Fix this by specifically printing an error for the VNOVOL error for
DoVolDelete call sites that used to print such an error. Do this for
all such sites except ones where we obviously print an error
immediately afterwards anyway.

This is just a quick targeted fix. A future more robust fix should
involve altering DoVolDelete to handle all of the different behaviors
expected by its various callers.

Change-Id: Ia79bce3d2fed4acd62d517064db5b6be77f6e987
Reviewed-on: http://gerrit.openafs.org/9704
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>