Adds tests for the `nonpoison::Mutex` variant by using a macro to
duplicate the existing `poison` tests.
Note that all of the tests here are adapted from the existing `poison`
tests.
Also steals the `test_mutex_arc_condvar` test from `mutex.rs`.
Signed-off-by: Connor Tsui <connor.tsui20@gmail.com>
This removes two minor OnceLock tests which test private methods. The
rest of the tests should be more than enough to catch mistakes in those
private methods. Also makes ReentrantLock::try_lock public. And finally
it makes the mpmc tests actually run.