This function is needed for Go 1.22, and is used from various packages
like math/rand.
When there is no random number generator available, it falls back to a
static sequence of numbers. I think this is fine, because as far as I
can see it is only used for non-cryptographic needs.
This function is used by the hash/maphash package.
Unfortunately, I couldn't get the hash/maphash package to pass tests
because it's too slow. I think it hits the quadratic complexity of the
current map implementation.