cleanup: set HA_PART_KEY_SEG for HA_KEY_ALG_LONG_HASH prefix keys

because they *are* prefix keys, even if long and hashed

sql/key.cc

@@ -441,8 +441,7 @@ void key_unpack(String *to, TABLE *table, KEY *key)
       }
     }
     field_unpack(to, key_part->field, table->record[0], key_part->length,
-                 MY_TEST(key_part->key_part_flag & HA_PART_KEY_SEG ||
-                     (key->algorithm == HA_KEY_ALG_LONG_HASH && key_part->length)));
+                 MY_TEST(key_part->key_part_flag & HA_PART_KEY_SEG));
  }
   dbug_tmp_restore_column_map(table->read_set, old_map);
   DBUG_VOID_RETURN;

sql/table.cc

@@ -1208,7 +1208,7 @@ bool parse_vcol_defs(THD *thd, MEM_ROOT *mem_root, TABLE *table,
                       new (mem_root)Item_field(thd, keypart->field),
                       new (mem_root) Item_int(thd, length));
           list_item->fix_fields(thd, NULL);
-         // keypart->key_part_flag |= HA_PART_KEY_SEG;
+          keypart->key_part_flag |= HA_PART_KEY_SEG;
         }
         field_list->push_back(list_item, mem_root);
       }