Apply clut changes only to one table.

The specification does not allow multiple bits to be set,
but some encoders do it anyway.
Applying it only to the first seems to give better results.
Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>

libavcodec/dvbsubdec.c

@@ -1015,9 +1015,9 @@ static void dvbsub_parse_clut_segment(AVCodecContext *avctx,
 
         if (depth & 0x80)
             clut->clut4[entry_id] = RGBA(r,g,b,255 - alpha);
-        if (depth & 0x40)
+        else if (depth & 0x40)
             clut->clut16[entry_id] = RGBA(r,g,b,255 - alpha);
-        if (depth & 0x20)
+        else if (depth & 0x20)
             clut->clut256[entry_id] = RGBA(r,g,b,255 - alpha);
     }
     }