Some specific tests are failing on macOS

[joojis]

The following tests are failing on macOS.

• register_and_deregister
• cannot_move_socket_to_other_event_loop
• register_to_the_same_event_loop

We need to skip them on macOS if we have no bandwidth to fix them, not to make developers confuse.

The test result is as follow:

running 4 tests
test service::tests::cannot_move_socket_to_other_event_loop ... FAILED
test service::tests::register_and_deregister ... FAILED
test service::tests::register_to_the_same_event_loop ... FAILED
test tests::service_register_handler ... ok

failures:

---- service::tests::cannot_move_socket_to_other_event_loop stdout ----
thread 'service::tests::cannot_move_socket_to_other_event_loop' panicked at 'called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" }', src/libcore/result.rs:999:5

---- service::tests::register_and_deregister stdout ----
thread 'service::tests::register_and_deregister' panicked at 'called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" }', src/libcore/result.rs:999:5

---- service::tests::register_to_the_same_event_loop stdout ----
thread 'service::tests::register_to_the_same_event_loop' panicked at 'called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" }', src/libcore/result.rs:999:5
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.


failures:
    service::tests::cannot_move_socket_to_other_event_loop
    service::tests::register_and_deregister
    service::tests::register_to_the_same_event_loop

test result: FAILED. 1 passed; 3 failed; 0 ignored; 0 measured; 0 filtered out

[foriequal0]

I've turned off these tests on Mac.
b1114b6