[xml] returning existing handler in xmlNewCharEncodingHandler

[<oliverst online de>]

patch against encoding.c version 1.77 as discussed with Igor on the list

1233a1234,1241
>      * Check for existing handler
>      */
>     handler = xmlFindCharEncodingHandler(name);
>
>     if (handler != NULL)
>         return(handler);
>
>     /*

So long
Oliver