don't call hooks when a query hasn't started

don't call hooks when a query hasn't started

guard the call to the NS_QUERY_RESET hook so it's called only if
the view has been set. If the view is NULL, it means the client has
been reset _before_ the query even started, and no other hook could
have been called, so it doesn't make sense to call this one.

this also enables us to avoid a NULL-check on the qctx->view in the
CALL_HOOK macros.