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.
t/issue293.t: added
C: unREADONLY before booting Coro::State (special-case Coro)
t/issue293: unTODO passing test. only one test so far
Changes: Coro fixes (#293)

reload Coro jit and SvREADONLY_off some of its XS symbols
CORE/re tests: wontfix #328, #329 re-eval with lexicals/globals

re-eval accessing globals with shadowed lexicals (same name) are not supported
and lexicals are also instable upstyream, using a broken Perl_sv_compile_2op_is_broken()
at regcomp.c:6819 compiler function.

TODO the other failing re CORE tests.
One new regression: re--reg_namedcapture==SIG-344.t