Add release version number.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@17696 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

Changelog

-version <next>
+version 0.5:
+
 - The "device" muxers and demuxers are now in a new libavdevice library
 - DV50 AKA DVCPRO50 encoder, decoder, muxer and demuxer
 - DV100 AKA DVCPRO HD decoder and demuxer