add test

Author: devnexen

ext/standard/tests/strings/gh18976.phpt

@@ -0,0 +1,18 @@
+--TEST--
+GH-15613 overflow on hex strings repeater value
+--FILE--
+<?php
+try {
+	pack('h2147483647');
+} catch (ValueError $e) {
+	echo $e->getMessage(), PHP_EOL;
+}
+try {
+	pack('H2147483647');
+} catch (ValueError $e) {
+	echo $e->getMessage(), PHP_EOL;
+}
+?>
+--EXPECT--
+Type h: integer overflow in format string
+Type H: integer overflow in format string