use libm remquo and copysign for a little speedup

[michaelkirk]

• [x] I agree to follow the project's code of conduct.

• [x] I added an entry to CHANGES.md if knowledge of this change could be valuable to users.

This makes our implement of sincosd look more like the cpp version, and still passes all the same tests.

$ cargo bench --bench="*" -- --baseline=4891fc4
    Finished bench [optimized] target(s) in 0.02s
     Running benches/geodesic_benchmark.rs (target/release/deps/geodesic_benchmark-cda172d0984b8505)
direct (c wrapper)/default
                        time:   [24.046 µs 24.071 µs 24.099 µs]
                        change: [-0.2131% +0.0210% +0.2593%] (p = 0.86 > 0.05)
                        No change in performance detected.
Found 9 outliers among 100 measurements (9.00%)
  3 (3.00%) low severe
  2 (2.00%) low mild
  1 (1.00%) high mild
  3 (3.00%) high severe

direct (rust impl)/default
                        time:   [26.129 µs 26.168 µs 26.211 µs]
                        change: [-5.5845% -5.3729% -5.1792%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 9 outliers among 100 measurements (9.00%)
  4 (4.00%) high mild
  5 (5.00%) high severe

inverse (c wrapper)/default
                        time:   [45.061 µs 45.141 µs 45.227 µs]
                        change: [+0.3738% +0.6326% +0.8919%] (p = 0.00 < 0.05)
                        Change within noise threshold.
Found 7 outliers among 100 measurements (7.00%)
  3 (3.00%) high mild
  4 (4.00%) high severe

inverse (rust impl)/default
                        time:   [67.739 µs 67.796 µs 67.865 µs]
                        change: [-3.2442% -3.0580% -2.8479%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 11 outliers among 100 measurements (11.00%)
  1 (1.00%) low severe
  5 (5.00%) low mild
  2 (2.00%) high mild
  3 (3.00%) high severe