Re: Crash during access_keymap

[Richard M. Stallman]

    Yeah, I only thought about the case that a pointer in the pure storage
    are changed so as to point to an impure object during the execution of
    a dumped one, but that may also occur in a dumping session.

Pure objects should never be changed; that's why it is ok to make them
pure.  The access primitives to modify slost in types that can be pure
are supposed to detect such an attempt and signal errors, with
CHECK_IMPURE

If any such primitive fails to use CHECK_IMPURE, let's just fix it.