cosmetics, add demuxer word

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@13422 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavformat/swfdec.c

 /*
- * Flash Compatible Streaming Format
+ * Flash Compatible Streaming Format demuxer
  * Copyright (c) 2000 Fabrice Bellard.
  * Copyright (c) 2003 Tinic Uro.
  *