v0.6.7-prover.2 — the parallel prover without its deadlock

Superseded by v0.6.7-prover.3: this build fixes only half of the hiding-RNG deadlock (Plonky3 #2363) and can still hang. Do not use it.

rand-prover only. v0.6.7-prover.1 plus one fix (commit 6430299, the same change as main's 4d5b039): Plonky3 0.7.0's HidingFriPcs held a spin lock around its RNG across rayon work, so on the parallel build a worker could steal another commit and spin on its own lock for ever. One pool member was wedged that way for five and a half hours. vendor/p3-fri is the crates.io 0.7.0 source with the lock taken only to fork a child RNG.

No consensus rule, wire format, verifier key or guest digest changes. Use it in place of v0.6.7-prover.1, which can deadlock.

Built on Ubuntu 24.04 from git archive 6430299 beside circuits aeacf31, cargo build --release --locked -p randprotocol-prover.

c07cecd091874e34ef55c5eb49566764047f364fc4f11bbe3dfe7863794db4cc  rand-prover