Use const thread_local #2993

Job	Run time
cargo +1.36 build (futures-{core, io, sink})	44s
cargo bench	55s
cargo hack check --feature-powerset	2m 25s
cargo minimal-versions build	25s
cargo +stable build	39s
cargo build --target thumbv7m-none-eabi	26s
cargo test (ubuntu-latest)	2m 41s
cargo +beta build	36s
cargo build --target thumbv6m-none-eabi	24s
cargo +1.63 build	1m 8s
cargo test (macos-latest)	5m 41s
cargo test (windows-latest)	4m 47s
cargo +nightly build	34s
cargo test (ubuntu-latest, aarch64-unknown-linux-gnu)	3m 27s
cargo clippy	24s
cargo test (ubuntu-latest, armv7-unknown-linux-gnueabihf)	6m 24s
cargo doc	18s
cargo test (ubuntu-latest, armv5te-unknown-linux-gnueabi)	6m 31s
cargo fmt	12s
cargo test (ubuntu-latest, i686-unknown-linux-gnu)	3m 26s
cargo miri test	14m 1s
cargo test -Z sanitizer=address	3m 22s
cargo test -Z sanitizer=memory	5m 44s
cargo test -Z sanitizer=thread	2m 28s
	1h 7m 42s

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