[PATCH] AArch64: Add ifunc masking tunable

[Wilco Dijkstra]

Hi Florian,

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

That would need various tunables to handle just the current settings, eg hwcap1,
hwcap2, cpuid and zva_size. I don't believe general HWCAP masking is safe since
it allows turning off security features like GCS or MTE... My goal is only to allow
forcing of a more generic ifunc - in principle it would be enough to force the
generic implementation, but supporting individual features was just as easy.

Cheers,
Wilco