RUSTSEC-2026-0385 Non-constant-time mask generation and `u128` comparisons

Summary The ctutils::Choice type has mask generation functions for each unsigned integer size u8, u16, u32, u64, u128. These are const fn and therefore can't reuse the asm!-backed mask generation in the cmov crate that's otherwise used to ensure constant-time. In releases prior to v0.4.4, the...