[PATCH] AArch64: Add ifunc masking tunable

[Florian Weimer]

* Wilco Dijkstra:

> Remove the glibc.cpu.name tunable since it's unused and out of date.
> Add a new feature to adjust ifunc selection for debugging and benchmarking
> (undocumented since this is for developers only).  If a flag bit is set,
> consider the feature disabled and defer to a more generic ifunc (-1 is
> the same as --disable-multiarch).

Maybe do something that is closer to a revert of this commit?

commit ad0aa1f54975bd20e30559930ea48a3568441ff4
Author: Stefan Liebler <stli@linux.ibm.com>
Date:   Fri Jun 7 13:42:43 2024 +0200

    elf: Remove LD_HWCAP_MASK / tunable glibc.cpu.hwcap_mask
    
    Remove the environment variable LD_HWCAP_MASK and the tunable
    glibc.cpu.hwcap_mask as those are not used anymore in common-code
    after removal in elf/dl-cache.c:search_cache().
    
    The only remaining user is sparc32 where it is used in
    elf_machine_matches_host().  If sparc32 does not need it anymore,
    we can get rid of it at all.  Otherwise we could also move
    LD_HWCAP_MASK / tunable glibc.cpu.hwcap_mask to be sparc32 specific.
    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

Thanks,
Florian