[PATCH v2 1/1] aarch64: simplify __libc_arm_za_disable failure path

[Wilco Dijkstra]

Hi Muhammad,
 
> The failure tail of __libc_arm_za_disable only leads to
> __libc_fatal, so it does not need to preserve call frame state.
>
> Remove the PAC prologue, frame setup, saved cntd value, stack
> stores, and associated CFI directives from the fatal path, leaving
> only the required SME state shutdown and fatal call.
>
> Add tst-sme-za-disable-fail to exercise the abort path by providing
> a TPIDR2 block with non-zero reserved bytes and checking that the
> process terminates with SIGABRT and the expected fatal message.

LGTM - committed.

Cheers,
Wilco