to @__passed__, @@__current__.
@passed is redefined in a few test suites, and this could lead to bugs.
Also rename @options (Runner#options) to @__runner_options__, which is
only used in make test-tool anyway.
because the name "MJIT" is an internal code name, it's inconsistent with
--jit while they are related to each other, and I want to discourage future
JIT implementation-specific (e.g. MJIT-specific) APIs by this rename.
[Feature #17490]