Add test ini_set with invalid time zone

Wasn't covered before according to gcov.php.net.

ext/date/tests/ini_set_incorrect.phpt

@@ -0,0 +1,10 @@
+--TEST--
+Test invalid time zone passed to ini_set
+--FILE--
+<?php
+
+ini_set("date.timezone", "Incorrect/Zone");
+
+?>
+--EXPECTF--
+Warning: ini_set(): Invalid date.timezone value 'Incorrect/Zone', we selected the timezone 'UTC' for now. in %sini_set_incorrect.php on line %d