`cc->cme` should not be marked.

cc is callcache.

cc->klass (klass) should not be marked because if the klass is
free'ed, the cc->klass will be cleared by `vm_cc_invalidate()`.

cc->cme (cme) should not be marked because if cc is invalidated
when cme is free'ed.
- klass marks cme if klass uses cme.
- caller classe's ccs->cme marks cc->cme.
- if cc is invalidated (klass doesn't refer the cc),
  cc is invalidated by `vm_cc_invalidate()` and cc->cme is
  not be accessed.
- On the multi-Ractors, cme will be collected with global GC
  so that it is safe if GC is not interleaving while accessing
  cc and cme.

fix [Bug #19436]

```ruby
10_000.times{|i|
  # p i if (i%1_000) == 0

  str = "x" * 1_000_000
  def str.foo = nil
  eval "def call#{i}(s) = s.foo"
  send "call#{i}", str
}
```

Without this patch:

```
real    1m5.639s
user    0m6.637s
sys     0m58.292s
```

and with this patch:

```
real    0m2.045s
user    0m1.627s
sys     0m0.164s
```

0 files changed, 0 insertions, 0 deletions