license header consistency cosmetics

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@15225 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavcodec/h264enc.c

 /*
  * H.264 encoder
  *
+ * This file is part of FFmpeg.
+ *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either