avx_sig: Adapt avx_sig test for Aarch64

[dchagin]

For now test succeed on Linux, fails on native and in the Linuxulator

[kib]

There are no XMM regs on aarch64.

[dchagin]

In D40309#917796, @kib wrote:

There are no XMM regs on aarch64.

I know, it was a quick fix to test some changes,
I propose to move inlined asm code to a separate file and rename xmm names to more general names.

Btw, under Linuxulator test works, I forgot to chroot before testing,
so only native fails.

[dchagin]

Rebase to D40312