bug #4207 json_encode error due to strftime returning non utf8 chars in Windows 8.1 Chinese version

Signed-off-by: Madhura Jayaratne <madhura.cj@gmail.com>

ChangeLog

@@ -3,6 +3,7 @@ phpMyAdmin - ChangeLog
 
 4.4.3.0 (not yet released)
 - bug #4851 PHP errors in login dialogue
+- bug #4207 json_encode error due to strftime returning non utf8 chars in Windows 8.1 Chinese version
 
 4.4.2.0 (2015-04-13)
 - bug #4835 PMA_hideShowConnection not called after submit_num_fields

libraries/Util.class.php

@@ -1610,7 +1610,14 @@ class PMA_Util
             $date
         );
 
-        return strftime($date, $timestamp);
+        $ret = strftime($date, $timestamp);
+        // Some OSes such as Win8.1 Traditional Chinese version did not produce UTF-8
+        // output here. See https://sourceforge.net/p/phpmyadmin/bugs/4207/
+        if (mb_detect_encoding($ret, 'UTF-8', true) != 'UTF-8') {
+            $ret = date('Y-m-d H:i:s', $timestamp);
+        }
+
+        return $ret;
     } // end of the 'localisedDate()' function
 
     /**