This way the decoder does not have to depend on the parser being initialized
before.
Patch by Laurent Aimar <fenrir at via dot ecp dot fr>.
Originally committed as revision 15986 to svn://svn.ffmpeg.org/ffmpeg/trunk
Consistently apply this rule: the guard name is obtained from the
filename by stripping the leading "lib", converting '/' and '.' to
'_' and uppercasing the resulting name. Guard names in the root
directory have to be prefixed by "FFMPEG_".
Originally committed as revision 15120 to svn://svn.ffmpeg.org/ffmpeg/trunk