Don't check directory nlink in stat tests

It seems like on many filesystems nlink for directories is the
number of subdirectories (plus two, due to . and ..). However,
this is not a POSIX requirement, and some filesystems don't
implement it this way. This seems to be the case for whatever is
used on the Travis AArch64 builders now.

Author: nikic

ext/standard/tests/file/lstat_stat_variation8.phpt

@@ -39,8 +39,8 @@ $new_stat = stat($dirname);
 // compare self stats
 var_dump( compare_self_stat($old_stat) );
 var_dump( compare_self_stat($new_stat) );
-// compare the stats
-$affected_members = array(3, 9, 10, 'nlink', 'mtime', 'ctime');
+// compare the stat
+$affected_members = array(9, 10, 'mtime', 'ctime');
 clearstatcache();
 var_dump(compare_stats($old_stat, $new_stat, $affected_members, "<"));