Explicitly allow unused crate dependencies and missing docs

[bearcage]

Without this annotation, the main file generated by trybuild will always raise a warning/error on the respective setting for these compiler lints.

Explicitly allowing it here should have the net result of letting tests written using trybuild handle just like any other test in an environment with that lint set, and otherwise not make a difference.

[bearcage]

Looks like on old versions of rust there's a smaller limit on how long an array of u8 can be while still impling write -- I tacked a to_vec on there to work around it (although adding an & would probably have worked too, now that I'm thinking about it).

[bearcage]

Aaah, unknown lint on 1.36. Guess I need to install it so I can check this locally - just a sec

[bearcage]

Github action sets -Dwarnings.

Allowing unknown lints (latest commit):

bearcage@site16:~/work/trybuild$ RUSTFLAGS=-Dwarnings cargo +1.36 test --all 2>/dev/null

running 12 tests
test path::test_path_macro ... ok
test normalize::tests::test_dir_backslash ... ok
test normalize::tests::test_basic ... ok
test normalize::tests::test_pyo3_url ... ok
test normalize::tests::test_dropshot_required_by ... ok
test normalize::tests::test_cargo_registry ... ok
test normalize::tests::test_proc_macro_panic ... ok
test normalize::tests::test_uniffi_out_dir ... ok
test normalize::tests::test_type_dir_backslash ... ok
test normalize::tests::test_strip_path_dependencies ... ok
test normalize::tests::test_rust_lib ... ok
test normalize::tests::test_traits_must_be_implemented ... ok

test result: ok. 12 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out


running 1 test
test test ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out


running 2 tests
test src/lib.rs -  (line 33) ... ok
test src/lib.rs -  (line 80) ... ok

test result: ok. 2 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

[dtolnay]

Thanks!