bench: bitstate: rework DFS implementation

* bench/bitstate/bitstate.hh: implementation here
9 jobs for ta/bitstate in 83 minutes and 55 seconds (queued for 40 minutes and 5 seconds)
Status Job ID Name Coverage
  Build
failed #83389
alpine-gcc

00:32:20

failed #83390
arch-clang

00:37:32

failed #83391
arch-gcc-glibcxxdebug

00:39:29

failed #83388
allowed to fail
debian-gcc-snapshot

00:06:32

failed #83386
debian-stable-gcc

00:26:06

failed #83387
debian-unstable-gcc-coverage

00:52:12

passed #83392
mingw-shared

00:10:02

passed #83393
mingw-static

00:08:22

failed #83394
armv7
raspbian

01:00:33

 
Name Stage Failure
failed
debian-stable-gcc Build
No job log
failed
debian-unstable-gcc-coverage Build
No job log
failed
debian-gcc-snapshot Build
No job log
failed
alpine-gcc Build
No job log
failed
arch-clang Build
No job log
failed
arch-gcc-glibcxxdebug Build
No job log
failed
raspbian Build
No job log