Fix wrong file name in header, noticed by David DeHaven, dave sagetv com.

Originally committed as revision 17158 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/x86/x86util.asm

 ;*****************************************************************************
-;* x86inc.asm
+;* x86util.asm
 ;*****************************************************************************
 ;* Copyright (C) 2008 Loren Merritt <lorenm@u.washington.edu>
 ;*