MDEV-18383: Missing rows with pushdown condition defined with IF-function

using Item_cond

This bug is similar to the bug MDEV-16765.
It appears because of the wrong pushdown into HAVING clause while this
pushdown shouldn't be made at all.
This happens because function that checks if Item_cond can be pushed
always returns that it can be pushed.

To fix it new method Item_cond::excl_dep_on_table() was added.

sql/item_cmpfunc.cc

@@ -4994,6 +4994,23 @@ Item *Item_cond::build_clone(THD *thd, MEM_ROOT *mem_root)
 }
 
 
+bool Item_cond::excl_dep_on_table(table_map tab_map)
+{
+  if (used_tables() & OUTER_REF_TABLE_BIT)
+    return false;
+  if (!(used_tables() & ~tab_map))
+    return true;
+  List_iterator_fast<Item> li(list);
+  Item *item;
+  while ((item= li++))
+  {
+    if (!item->excl_dep_on_table(tab_map))
+      return false;
+  }
+  return true;
+}
+
+
 bool Item_cond::excl_dep_on_grouping_fields(st_select_lex *sel)
 {
   List_iterator_fast<Item> li(list);