This way we have for instance
  (Inf(1) | Fin(2)) & (Fin(1) | Inf(3)) & Inf(0)
converted into just
  (Fin(1) & Fin(2) & Inf(0)) | (Inf(0)&Inf(1)&Inf(3))
while previously we would produce 4 terms:
  (Fin(2) & Fin(1) & Inf(0)) | (Fin(2) & (Inf(0)&Inf(3)))
  | (Fin(1) & (Inf(0)&Inf(1))) | (Inf(0)&Inf(1)&Inf(3))

* src/tgba/acc.cc (to_dnf): Recode it.
* src/tgbatest/acc2.test: Adjust.