- Inplace alter shouldn't set default date column as '0000-00-00' when
table is not empty. So mysql_inplace_alter_table() copied
alter_ctx.error_if_not_empty to a new field of Alter_inplace_info.
In ha_innobase::check_if_supported_inplace_alter() should check the
error_if_not_empty flag and return INPLACE_NOT_SUPPORTED if the table
is not empty