RttTestSample failure in crates/tor-congestion/src/rtt.rs

Whilst preparing my Mac for our trip to Ireland, I tried to run the Arti test suite there with a aarch64-apple-darwin build. Everything seems to compile fine, but we have a test failure here:

running 2 tests
test rtt::test::clock_skew_test_vectors ... ok
test rtt::test::rtt_test_vectors ... FAILED

failures:

---- rtt::test::rtt_test_vectors stdout ----
testing RttTestSample { sent_nsec: 100, sendme_received_nsec: 200, last_rtt_out_nsec: 100, ewma_rtt_out_nsec: 100, min_rtt_out_nsec: 100 }
thread 'rtt::test::rtt_test_vectors' panicked at 'assertion failed: `(left == right)`
  left: `83ns`,
 right: `100ns`', crates/tor-congestion/src/rtt.rs:335:13
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace


failures:
    rtt::test::rtt_test_vectors

test result: FAILED. 1 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

This looks a bit like a timer that may be a bit too eager here compared to other platforms, but I will let @eta think about this and we can eventually try it out on my Mac in Ireland while we are there if you have any obvious solutions to this.

I won't have time to look at it until during or after Ireland, unfortunately.

Here's some toolchain information if that is helpful:

% rustup show
Default host: aarch64-apple-darwin
rustup home:  /Users/ahf/.rustup

stable-aarch64-apple-darwin (default)
rustc 1.63.0 (4b91a6ea7 2022-08-08)