[PATCH][AArch64] Improve aarch64_case_values_threshold setting

[Wilco Dijkstra]

James Greenhalgh wrote:
> As this change will change code generation for all cores (except
> Exynos-M1), I'd like to hear from those with more detailed knowledge of
> ThunderX, X-Gene and qdf24xx before I take this patch.
>
> Let's give it another week or so for comments, and expand the CC list.

Note it affect Exynos-M1 as well with -O2. 

>> GCC is ~1.2% faster on Cortex-A53 built for generic, but there is no
>> difference in perlbench.
>
> Where were these changes if not perlbench?

In the GCC test.

Wilco