Lock all relations referred to in updatable views

Lock all relations referred to in updatable views

Even views considered "simple" enough to be automatically updatable may
have mulitple relations involved (eg: in a where clause).  We need to
make sure and lock those relations when rewriting the query.

Back-patch to 9.3 where updatable views were added.

Pointed out by Andres, patch thanks to Dean Rasheed.