Several block/ files are relying on qerror.h being provided by
qapi-types.h. Fix this, as a future commit will change qapi-types.h
not to provide qerror.h.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>