Skip test if libxml does not support GBK encoding

Author: arnaud-lb

ext/xmlwriter/tests/xmlwriter_toStream_encoding_gbk.phpt

@@ -2,6 +2,21 @@
 XMLWriter::toStream() with encoding - test GBK
 --EXTENSIONS--
 xmlwriter
+--SKIPIF--
+<?php
+$h = fopen("php://output", "w");
+
+$writer = XMLWriter::toStream($h);
+
+libxml_use_internal_errors(true);
+$writer->startDocument(encoding: "GBK");
+
+foreach (libxml_get_errors() as $error) {
+    if (trim($error->message) === 'xmlTextWriterStartDocument : unsupported encoding') {
+        die('skip libxml does not support GBK encoding');
+    }
+}
+?>
 --FILE--
 <?php