Don't create empty HTAB in package, if it is not necessary

Author: CherkashinSergey

expected/pg_variables_trans.out

@@ -1794,7 +1794,8 @@ SELECT package FROM pgv_stats() ORDER BY package;
  package 
 ---------
  vars
-(1 row)
+ vars2
+(2 rows)
 
 SELECT * FROM pgv_list() ORDER BY package, name;
  package | name | is_transactional