bug#50153: call-with-values outside tail position + backtrace + compilation causes segfault

Hi guilers,

Write the following to "crash.scm":

> (call-with-values backtrace list)
> #t

(the trailing #t is important) and run

> # --auto-compile works too, but --no-auto-compile doesn't cause a crash
> guile --fresh-auto-compile -l crash.scm

it will segfault during the printing of the backtrace:

>  Backtrace:
>  In ice-9/boot-9.scm:
>    1752:10  8 (with-exception-handler _ _ #:unwind? _ #:unwind-for-type _)
>  In unknown file:
>             7 (apply-smob/0 #<thunk 7f1390524080>)
>  In ice-9/boot-9.scm:
>      724:2  6 (call-with-prompt _ _ #<procedure default-prompt-handler (k proc)>)
>  In ice-9/eval.scm:
>      619:8  5 (_ #(#(#<directory (guile-user) 7f139052ac80>)))
>  In ice-9/boot-9.scm:
>     2835:4  4 (save-module-excursion _)
>    4380:12  3 (_)
>  In [...]/crash.scm:
>       36:0  2 (segfault)
>  In unknown file:
>  Segmentatiefout

Greetings,
Maxime.

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