Description:
------------
After setting script locale to ru_RU.UTF-8, behavior of functions 
strtoupper and atrtolower becomes unpredictable. Function setlocale, 
reports that encoding is setted to desired. But case conversion make 
no changes or change letters incorrectly (results may vary).




Reproduce code:
---------------
<?php
header('Content-type: text/html; charset=utf-8');
$sL = '?????????????????????????????????'; // lower russian alphabet, source file must be in utf-8 encoding
$sU = '?????Ũ??????????????????????????'; // upper russian alphabet
echo setlocale(LC_ALL, 'ru_RU.UTF-8') .'<br>';
echo 'Lower to upper:<br>';
echo strtoupper($sL) .'<br>'; // incorrect result
echo mb_strtoupper($sL, 'utf-8') .'<br>'; // correct result, for comparsion
echo 'Upper to lower:<br>';
echo strtolower($sU) .'<br>'; // incorrect result
echo mb_strtolower($sU, 'utf-8') .'<br>'; // correct result, for comparsion
?>


Expected result:
----------------
ru_RU.UTF-8
Lower to upper:
?????Ũ??????????????????????????
?????Ũ??????????????????????????
Upper to lower:
?????????????????????????????????
?????????????????????????????????




Actual result:
--------------
ru_RU.UTF-8
Lower to upper:
?????̸??????????????????????????
?????Ũ??????????????????????????
Upper to lower:
&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;
?????????????????????????????????