[Bug libgcc/124050] libgcc unwinder incorrectly handles signal frames without the machine-specific fallback

[hpa at zytor dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124050

--- Comment #5 from H. Peter Anvin <hpa at zytor dot com> ---
It isn't just glibc, either; on legacy platforms that used to use the stack it
is handled by the vdso these days.

The real question is: is the signal frame flag actually picked up, or not?