ZP-796 Replace ftruncate with Utf8_stream_ftruncate.

Released under the Affero GNU General Public License (AGPL) version 3.
Signed-off-by: Etienne CHAMPETIER <champetier.etienne@gmail.com>

src/backend/zarafa/mapiprovider.php

@@ -2484,7 +2484,7 @@ class MAPIProvider {
                     $message->asbody->estimatedDataSize > $bpo->GetTruncationSize()
                 ) {
                 // truncate data stream
-                ftruncate($message->asbody->data, $bpo->GetTruncationSize());
+                $message->asbody->data = Utils::Utf8_stream_ftruncate($message->asbody->data, $bpo->GetTruncationSize());
                 $message->asbody->truncated = 1;
             }
             // set the preview or windows phones won't show the preview of an email