vl: Fail right after first bad -object

vl: Fail right after first bad -object

Failure to create an object with -object is a fatal error.  However,
we delay the actual exit until all -object are processed.  On the one
hand, this permits detection of genuine additional errors.  On the
other hand, it can muddy the waters with uninteresting additional
errors, e.g. when a later -object tries to reference a prior one that
failed.

We generally stop right on the first bad option, so do that for
-object as well.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>