Remove unnecessary unsafe from time refcount rules - #495

Three clock-ID helper functions in the time refcount rules were declared unsafe even though they only return nix::time::ClockId constants.

• rules/time/tgt_refcount.rs
  • Dropped unsafe from f9 (CLOCK_REALTIME), f10 (CLOCK_MONOTONIC) and f11 (CLOCK_MONOTONIC_RAW, Linux only).

// before
unsafe fn f9() -> nix::time::ClockId { nix::time::ClockId::CLOCK_REALTIME }
// after
fn f9() -> nix::time::ClockId { nix::time::ClockId::CLOCK_REALTIME }

I haven't built this or run the tests. Please check CI to confirm the rules still compile and the translated output is unchanged.

• Fixes Remove unsafe from time refcount rules #453