Add fairness to futures_util::{select, try_select, select_ok} #2235

Job	Run time
cargo +1.36 build (futures-{core, io, sink})	1m 48s
cargo +1.56 build	1m 45s
cargo +stable build	1m 23s
cargo +beta build	1m 18s
cargo +nightly build	1m 2s
cargo test (ubuntu-latest)	4m 38s
cargo test (macos-latest)	6m 35s
cargo test (windows-latest)	6m 29s
cargo test (ubuntu-latest, aarch64-unknown-linux-gnu)	4m 32s
cargo test (ubuntu-latest, armv7-unknown-linux-gnueabihf)	8m 10s
cargo test (ubuntu-latest, armv5te-unknown-linux-gnueabi)	11m 4s
cargo test (ubuntu-latest, i686-unknown-linux-gnu)	5m 0s
cargo bench	1m 33s
codegen	30s
cargo minimal-versions build	49s
cargo hack check --feature-powerset	3m 21s
cargo build --target thumbv7m-none-eabi	42s
cargo build --target thumbv6m-none-eabi	37s
cargo clippy	41s
cargo doc	25s
cargo fmt	12s
cargo miri test	10m 6s
cargo test -Z sanitizer=address	3m 59s
cargo test -Z sanitizer=memory	3m 3s
cargo test -Z sanitizer=thread	2m 55s
	1h 22m 37s

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