runtime: segfault running ppc64/linux binaries with kernel 5.18

[pmur]

While testing go on a ppc64/linux and 5.18.0 on debian sid, all go binaries segfault shortly after starting up.

This seems to have happened between kernel 5.10 and 5.18. R0 is set to '0xb' by the kernel, which breaks early startup code.

[gopherbot]

Change https://go.dev/cl/424927 mentions this issue: runtime: fix ppc64 startup on newer linux kernels

[pmur]

@gopherbot please consider a backport to 1.19 and 1.18.

[gopherbot]

Backport issue(s) opened: #54664 (for 1.18), #54665 (for 1.19).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases.