Shared: fix shared futures missing wake up #2923

Job	Run time
cargo +1.36 build (futures-{core, io, sink})	59s
cargo +stable build	40s
cargo +1.56 build	1m 26s
cargo test (ubuntu-latest)	3m 16s
cargo +beta build	42s
cargo +nightly build	34s
cargo bench	54s
cargo test (macos-latest)	6m 47s
cargo clippy	15s
cargo test (windows-latest)	5m 20s
cargo test (ubuntu-latest, aarch64-unknown-linux-gnu)	6m 38s
cargo doc	17s
cargo hack check --feature-powerset	2m 26s
cargo fmt	4s
cargo test (ubuntu-latest, armv7-unknown-linux-gnueabihf)	12m 28s
cargo test (ubuntu-latest, armv5te-unknown-linux-gnueabi)	13m 11s
cargo minimal-versions build	27s
cargo test (ubuntu-latest, i686-unknown-linux-gnu)	3m 52s
cargo miri test	1h 4m 58s
cargo build --target thumbv7m-none-eabi	25s
cargo build --target thumbv6m-none-eabi	24s
cargo test -Z sanitizer=address	4m 38s
cargo test -Z sanitizer=memory	5m 9s
cargo test -Z sanitizer=thread	3m 22s
	2h 19m 12s

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