a fix in libmysql.c

libmysql/libmysql.c:
  This crashed my mysql client.
  I hope that fix is correct.

libmysql/libmysql.c

@@ -1173,7 +1173,7 @@ unpack_fields(MYSQL_DATA *data,MEM_ROOT *alloc,uint fields,
       if (INTERNAL_NUM_FIELD(field))
         field->flags|= NUM_FLAG;
       if (default_value && row->data[6])
-        field->def=strdup_root(alloc,(char*) row->data[8]);
+        field->def=strdup_root(alloc,(char*) row->data[6]);
       else
         field->def=0;
       field->max_length= 0;