Using __builtin_unwind_init in glibc

Using __builtin_unwind_init in glibc

[Florian Weimer]

I would like to use __builtin_unwind_init in glibc in a few places, to
preserve additional evidence for a debugger.  It's currently not a
documented built-in function.  Would that still be okay.

(Most architectures will have probably benefit from a custom
register-preserving assembler trampoline, but __builtin_unwind_init
would still be very useful for generic code.)

Thanks,
Florian