update copyright year, it looks odd otherwise :)

Originally committed as revision 6830 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/eval.c

 /*
  * simple arithmetic expression evaluator
  *
- * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
+ * Copyright (c) 2002-2006 Michael Niedermayer <michaelni@gmx.at>
  * Copyright (c) 2006 Oded Shimon <ods15@ods15.dyndns.org>
  *
  * This file is part of FFmpeg.