Make elf_aux_info() as public libc function.

[mmel]

Summary

• Teach elf aux vector functions about newly added AT_HWCAP ATHWCAP2 vectors.
• Export _elf_aux_info() as new public libc function elf_aux_info(3)

The elf_aux_info(3) should be considered as FreeBSD counterpart of glibc
getauxval() with more robust interface.

Note:
We cannot name this new function as getauxval(), with glibc compatible
interface. Some ports autodetect its existence and then expects that all
Linux specific AT_<*> vectors are defined and implemented.

[kib]

This looks mostly fine, but is not committable because AT_HWCAP2 is not defined.

Does it make sense to include machine/elf.h from auxv.h ? Why not make it a user duty ?

Would be nice to provide some kind of man page.

[kib]

sys/sys/auxv.h

35 ↗

(On Diff #34180)

You need to brace the function declaration into BEGIN_DECLS/END_DECLS to make it usable for C++.

[mmel]

In D12743#264414, @kib wrote:

Does it make sense to include machine/elf.h from auxv.h ? Why not make it a user duty ?

Imho yes, AT_ values are defined in machine/elf.h so user should include it in (almost) all cases.

Would be nice to provide some kind of man page.

I will ask Ian for man page, this kind of job is significantly out of my skill (even in my native language). My bad I known.

sys/sys/auxv.h

35 ↗

(On Diff #34180)

Ahh, yes, sure. I will do it.