these are no longer used for anything
Completed CI build of recent patches (with random distcheck fail due to missing D6877):
Its been a while since you submitted this. Since the I can see 8 commits in src/benchmarks and a complete new benchmark for focus widget tree being added. I would not call it unused.
It also works fine with ninja benchmark for me.
There has been exactly 1 functional change to this directory since 2016 (I stopped looking through history at this point). It's worth keeping the focus benchmark which was just added, but nothing else seems useful/used in any way.