add test

Author: devnexen

ext/standard/tests/strings/gh19898.phpt

@@ -0,0 +1,11 @@
+--TEST--
+GH-18976 (pack overflow with h/H format)
+--INI--
+memory_limit=-1
+--FILE--
+<?php
+str_repeat("1", (int)str_repeat("1", 2147483648));
+echo "OK"
+?>
+--EXPECT--
+OK