Clear input/output buffers on macOS upon TTY open #307

Job	Run time
lint	37s
cargo-deny (advisories)	16s
cargo-deny (bans licenses sources)	15s
aarch64-apple-darwin / build	1m 18s
aarch64-apple-ios / build	2m 10s
aarch64-unknown-linux-gnu / build	52s
aarch64-unknown-linux-musl / build	1m 9s
arm-linux-androideabi / build	37s
armv7-linux-androideabi / build	34s
i686-pc-windows-gnu / build	2m 14s
i686-pc-windows-msvc / build	2m 9s
msrv / build	1m 17s
i686-unknown-linux-gnu / build	42s
i686-unknown-linux-musl / build	1m 20s
x86_64-apple-darwin / build	2m 0s
x86_64-pc-windows-gnu / build	2m 33s
x86_64-pc-windows-msvc / build	2m 5s
x86_64-unknown-freebsd / build	41s
x86_64-unknown-linux-gnu / build	1m 21s
x86_64-unknown-linux-musl / build	1m 13s
x86_64-unknown-netbsd / build	31s
	25m 54s

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