bug#41321: 27.0.91; Emacs aborts due to invalid pseudovector objects

[Stefan Monnier]

>> This shouldn't be a problem: wide-int builds use MSB tagging, so all
>> Lisp_Objects which contain a pointer have their lowest 32bits exactly
>> identical to that pointer (and the higher 32bits just contain the tag).
> As I said, I don't believe that's true for symbols.  Qnil is always
> binary 0, so we offset all symbols by the offset of lispsym.

Oh, right, good point: I had completely forgotten about that "detail".
We should probably adjust our conservative stack scanning accordingly.


        Stefan