Add missing authors to copyright headers.

Originally committed as revision 26133 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/x86/h264_intrapred.asm

 ;******************************************************************************
 ;* H.264 intra prediction asm optimizations
 ;* Copyright (c) 2010 Jason Garrett-Glaser
+;* Copyright (c) 2010 Holger Lubitz
+;* Copyright (c) 2010 Loren Merritt
+;* Copyright (c) 2010 Ronald S. Bultje
 ;*
 ;* This file is part of FFmpeg.
 ;*