Do not use deprecated CLI option

Author: sebastianbergmann

build.xml

@@ -383,7 +383,6 @@
             <arg value="--config" />
             <arg path="${basedir}/build/config/php-scoper.php" />
             <arg value="--no-interaction" />
-            <arg value="--stop-on-failure" />
             <arg value="--output-dir" />
             <arg path="${basedir}/build/tmp/phar-scoped" />
             <arg value="--prefix" />