Add regression test for bug #76770

Closes GH-3514.

Author: sam002

ext/date/tests/bug76770.phpt

@@ -0,0 +1,8 @@
+--TEST--
+Bug #76770 'U' modifier in 'datetime::createFromFormat' adds seconds to other specifiers
+--FILE--
+<?php
+var_dump(datetime::createFromFormat('U H', '3600 01')->getTimestamp());
+?>
+--EXPECT--
+int(3600)