Merge commit '1a094af6'

This commit is a no-op. The value of the refactoring is dubious and
merging it is error prone. If someone feels strongly about merging it,
let me know, and I will.

* commit '1a094af6':
  fft: Split MDCT bits off from FFT
Merged-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>