Use TZ similar to easter_date.phpt else gcov et al give a diff for unixtojd(1000000000)

Author: cjbj

ext/calendar/tests/unixtojd.phpt

@@ -4,6 +4,7 @@ unixtojd()
 <?php include 'skipif.inc'; ?>
 --FILE--
 <?php
+putenv('TZ=UTC');
 echo unixtojd(40000). "\n";
 echo unixtojd(1000000000). "\n";
 echo unixtojd(1152459009). "\n";