Fix undeclared variable in stat tests

Closes phpGH-12645

Author: iluuu1994

ext/standard/tests/file/file.inc

@@ -590,9 +590,9 @@ $all_stat_keys = array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
                        "rdev", "size", "atime", "mtime", "ctime",
                        "blksize", "blocks");
 
-$stat_time_diff_keys = array(8, 'atime');
-
 function compare_stats($stat1, $stat2, $fields, $op = "==", $flag = false ) {
+  $stat_time_diff_keys = array(8, 'atime');
+
   // dump the stat if requested
   if ( $flag == true ) {
     var_dump($stat1);