Shared: fix shared futures missing wake up #2924

Job	Run time
cargo bench	57s
cargo clippy	14s
cargo +1.36 build (futures-{core, io, sink})	1m 15s
cargo +stable build	41s
cargo doc	18s
cargo +beta build	40s
cargo hack check --feature-powerset	2m 26s
cargo fmt	4s
cargo +nightly build	36s
cargo minimal-versions build	24s
cargo miri test	1h 4m 59s
cargo build --target thumbv7m-none-eabi	26s
cargo test -Z sanitizer=address	4m 24s
cargo build --target thumbv6m-none-eabi	25s
cargo test -Z sanitizer=memory	4m 51s
cargo test (ubuntu-latest)	3m 6s
cargo +1.56 build	1m 52s
cargo test -Z sanitizer=thread	3m 8s
cargo test (macos-latest)	6m 0s
cargo test (windows-latest)	5m 25s
cargo test (ubuntu-latest, aarch64-unknown-linux-gnu)	6m 37s
cargo test (ubuntu-latest, armv7-unknown-linux-gnueabihf)	12m 18s
cargo test (ubuntu-latest, armv5te-unknown-linux-gnueabi)	13m 11s
cargo test (ubuntu-latest, i686-unknown-linux-gnu)	3m 41s
	2h 17m 58s

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