Just a little refactoring

[tattn]

No description provided.

[nobu]

After vm_pop_frame(), *reg_cfp may be invalid.
It must be like:

    finished = VM_FRAME_TYPE_FINISH_P(GET_CFP());
    vm_pop_frame(th);
    if (UNLIKELY(finished)) {

I'm afraid the current code is simple enough.

[k0kubun]

The current master branch does not seem to have this problem. Closing, thank you.