Merge #24

24: Update parking_lot dependency to 0.12 r=bertptrs a=djkoloski

The changelog for parking_lot 0.12 can be found [here](https://github.com/Amanieu/parking_lot/blob/master/CHANGELOG.md#parking_lot-0120-parking_lot_core-090-lock_api-046-2022-01-28):
```
- The MSRV is bumped to 1.49.0.
- Disabled eventual fairness on wasm32-unknown-unknown. (#302)
- Added a rwlock method to report if lock is held exclusively. (#303)
- Use new asm! macro. (#304)
- Use windows-rs instead of winapi for faster builds. (#311)
- Moved hardware lock elision support to a separate Cargo feature. (#313)
- Removed used of deprecated spin_loop_hint. (#314)
```

Co-authored-by: David Koloski <dkoloski@google.com>

Cargo.toml

@@ -20,7 +20,7 @@ rustdoc-args = ["--cfg", "docsrs"]
 [dependencies]
 lazy_static = "1"
 lock_api = { version = "0.4", optional = true }
-parking_lot = { version = "0.11", optional = true }
+parking_lot = { version = "0.12", optional = true }
 
 [dev-dependencies]
 criterion = "0.3"