Fix undersized size field in FLAC extradata.
Fix undersized size field in FLAC extradata.

Causes XiphQT to reliably infinite-loop in the UI
thread on some files.


MaddTheSane/perian,MaddTheSane/perian,MaddTheSane/perian,MaddTheSane/perian,MaddTheSane/perian,MaddTheSane/perian