addresses #1152

no longer reference key_part->null_offset because add_index does not
set the value

git-svn-id: file:///svn/mysql/tokudb-engine/src@6126 c7de825b-a66e-492c-adef-691d508d4ae1

storage/tokudb/ha_tokudb.cc

@@ -1817,7 +1817,9 @@ DBT* ha_tokudb::create_dbt_key_from_key(DBT * key, KEY* key_info, uchar * buff,
         //
         if (key_part->field->null_bit) {
             /* Store 0 if the key part is a NULL part */
-            if (record[key_part->null_offset] & key_part->field->null_bit) {
+            uint null_offset = (uint) ((char*) key_part->field->null_ptr
+                            - (char*) table->record[0]);
+            if (record[null_offset] & key_part->field->null_bit) {
                 *buff++ = 0;
                 *has_null = true;
                 //