Fix blend_subrect for some subrects positioned on odd rows.

Patch by Björn Axelsson gecko A acc D umu D se

Originally committed as revision 17014 to svn://svn.ffmpeg.org/ffmpeg/trunk

ffplay.c

@@ -498,8 +498,8 @@ static void blend_subrect(AVPicture *dst, const AVSubtitleRect *rect, int imgw,
             p++;
             lum++;
         }
-        p += wrap3 + (wrap3 - dstw * BPP);
+        p += wrap3 - dstw * BPP;
-        lum += wrap + (wrap - dstw - dstx);
+        lum += wrap - dstw - dstx;
         cb += dst->linesize[1] - width2 - skip2;
         cr += dst->linesize[2] - width2 - skip2;
     }