Replace item->marker= # with Item->marker= DEFINE

- Better, easier to read code (no used of 'random' constants).
- All defines are now unique, so it is easier to find bugs if
  somethings goes wrong.

Other things:
- Created sub function of common code in Aggregator_distinct::setup() and
  Item_func_group_concat::setup() that set item->marker
- More documentation
- Folded a few long lines.
- Allmost all changes in item.cc, sql_lex.cc and sql_window.cc are done
  with 'replace'.

1 files changed, 2 insertions, 2 deletions

diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index 2a6f8ae57db..35735b18168 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -7549,7 +7549,7 @@ Item_equal::excl_dep_on_grouping_fields(st_select_lex *sel)
   {
     if (item->excl_dep_on_grouping_fields(sel))
     {
-      set_extraction_flag(FULL_EXTRACTION_FL);
+      set_extraction_flag(MARKER_FULL_EXTRACTION);
       return true;
     }
   }
@@ -7663,7 +7663,7 @@ bool Item_equal::create_pushable_equalities(THD *thd,
     if (!eq ||  equalities->push_back(eq, thd->mem_root))
       return true;
     if (!clone_const)
-      right_item->set_extraction_flag(IMMUTABLE_FL);
+      right_item->set_extraction_flag(MARKER_IMMUTABLE);
   }
 
   while ((item=it++))