ov_bitrate misbehaviour with gcc3 + optimizations
When ov_bitrate(&vf,-1) (on the whole stream) from libvorbis 1.0 compiled with
gcc3.2 (also happens with gcc 3.1) and default optimizations is called on a
seekable file it returns -2147483648 regardless of the file. (On a nonseekable
file getting the nominal bitrate works fine) When compiled with ``make debug''
(and so optimizations disabled) it doesn't occur.