- ARM assembly version of parts of mdct,
- special case for vorbis_book_decodevv_add for 2 channels and even book->dim,
- store the output in vb->pcm if possible, as it is usually in IRAM as
opposed to v->pcm.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@14875 a1c6a512-1295-4272-9138-f99709370657
