Avoid choosing an invalid index as primary key

Fixing the other functions selecting pg_index (as in Josh original patch)
doesn't seem necessary as they are only called with an index oid, and we
should only call them with a valid index as argument.

lib/pg_reorg.sql.in

@@ -157,6 +157,7 @@ CREATE VIEW reorg.primary_keys AS
   SELECT indrelid, (reorg.array_accum(indexrelid))[1] AS indexrelid
     FROM (SELECT indrelid, indexrelid FROM pg_index
    WHERE indisunique
+     AND indisvalid
      AND 0 <> ALL(indkey)
      AND NOT EXISTS(
            SELECT 1 FROM pg_attribute