* src/eval.c (call_debugger, signal_or_quit):
Raise extra headroom to 200 levels.  The debugger is sometimes entered
via handler-bind so we raise the bar there as well (bug#80154).

* src/igc.c (igc_assert_not_an_mps_object): New function.
* src/eval.c (record_unwind_protect_ptr):
(record_unwind_protect_ptr_mark):
(record_unwind_protect_module): Use it.

* src/lisp.h (record_in_backtrace): Don't record the argument address as
stack_top because most of the time it won't be on the C stack at all.
* src/eval.c (eval_sub): Do it here instead using an address guaranteed
to be on the C stack and we are just in the Lisp interpreter anyway.

* src/eval.c (signal_or_quit): Signal an error if 'signal' gets called
with an invalid error symbol.