This removes the need to check the offset every release.
I've also removed the negative build tag from runtime_amd64.go, which less
obviously correct. In theory, we should check that this package's use of
nmspinning is still valid in each release, but there is no way to automate that
and I don't realistically seeing checking happening beyond verifying tests
work. Additionally, the existing use is already suspect. :)
The good news is the misuse is likely to cause scheduling issues, not memory
corruption.
PiperOrigin-RevId: 505114683
Michael Pratt