add tests

Author: devnexen

ext/iconv/tests/gh21664.phpt

@@ -0,0 +1,21 @@
+--TEST--
+GH-21664 (iconv_mime_decode/iconv_mime_encode bailout corruption)
+--EXTENSIONS--
+iconv
+--FILE--
+<?php
+$r = iconv_mime_decode("=?utf-8?Q?" . chr(0xA1) . "?= .");
+var_dump($r);
+
+$r = iconv_mime_encode("Subject", "\x80", ["input-charset" => "UTF-8", "output-charset" => "UTF-8"]);
+var_dump($r);
+
+echo "Done\n";
+?>
+--EXPECTF--
+Notice: iconv_mime_decode(): Detected an illegal character in input string in %s on line %d
+bool(false)
+
+Notice: iconv_mime_encode(): Detected an illegal character in input string in %s on line %d
+bool(false)
+Done