t/e_perlcc.t: TODO 77 --check test. still fails on travis
C: special-case Coro jit

need to force reloading Coro::State::_jit, so that Coro::State::_jit
gets a proper ROOT assigned and the CV saved as such.
WIP In the boot_Coro__State step we now fall into READONLY no_modify croaks.