post-merge: --ps-protocol fixes

Includes:

MDEV-17302 Add support for ALTER USER command in prepared statement

and

MDEV-17673 main.cte_recursive fails in bb-10.4-ps branch in --ps

  Set correct SELECT_LEX linkage for recursive CTEs.
  Do not delegate this job to TABLE_LIST::set_as_with_table,
  because it is only run on prepare, while With_element::move_anchors_ahead
  is run both on prepare and execute (fix by Igor)

sql/sql_cte.cc

@@ -689,6 +689,7 @@ void With_element::move_anchors_ahead()
     }
   }
   first_recursive= new_pos;
+  spec->first_select()->linkage= DERIVED_TABLE_TYPE;
 }