Remove spurious variable from autogen.sh.
Remove spurious variable from autogen.sh.

nicolaichuk/vorbis,mwgoldsmith/vorbis,ShiftMediaProject/vorbis,nicolaichuk/vorbis,ShiftMediaProject/vorbis,mwgoldsmith/vorbis,ShiftMediaProject/vorbis,erikd/vorbis,erikd/vorbis,ShiftMediaProject/vorbis,nicolaichuk/vorbis,mwgoldsmith/vorbis,erikd/vorbis,erikd/vorbis,ShiftMediaProject/vorbis,ShiftMediaProject/vorbis,mwgoldsmith/vorbis,nicolaichuk/vorbis