Improved storage size for Item, Field and some other classes

- Changed order of class fields to remove dead alignment space.
- Changed bool fields in Item to bit fields.
- Used packed enum's for some fields in common classes
- Removed not used Item::rsize.
- Changed some class variables from uint/int to smaller type int's.
- Ensured that field_index is uint16 in all classes and functions. Fixed
  also that we proparly compare with NO_CACHED_FIELD_INDEX when checking
  if variable is not set.
- Removed checking of highest bit of unireg_check (has not been used in
  a long time)
- Fixed wrong arguments to make_cond_for_table() for join_tab_idx_arg
  from false to 0.

One of the result was reducing the size if class Item with ~24 bytes

1 files changed, 2 insertions, 1 deletions

diff --git a/sql/item_sum.cc b/sql/item_sum.cc
index 537eaaf8dcd..71759169376 100644
--- a/sql/item_sum.cc
+++ b/sql/item_sum.cc
@@ -890,7 +890,8 @@ bool Aggregator_distinct::setup(THD *thd)
       mem_root.
     */
 
-    item_sum->null_value= item_sum->maybe_null= 1;
+    item_sum->null_value= 1;
+    item_sum->maybe_null= 1;
     item_sum->quick_group= 0;
 
     DBUG_ASSERT(item_sum->get_arg(0)->is_fixed());