_ioperm support for Arm

[Florian Weimer]

* Adhemerval Zanella:

[sysctl deprecation]

>> The linker warnings happen only on some architectures right now (which
>> use the “generic” Linux system call ABI).
>
> This is standard ENOSYS stub we emit for non-implemented symbols. I think
> we will need both add __attribute_deprecated__ and create a new stub with
> a different warning message (maybe "symbol is deprecated and it will be 
> removed in future versions").

We have an explicit sysdeps/unix/sysv/linux/generic/sysctl.c override,
though.  I don't know why it was done this way.  I think it predates the
attempt to deprecate sysctl with the addition of the x32 ABI.

Anyway, it doesn't matter for the upcoming deprecation.

Thanks,
Florian