Optimize jobserver `try_acquire` #1424

Job	Run time
Clippy	6s
Test build-std (aarch64-tvos)	5m 19s
Test build-std (aarch64-tvos-sim)	4m 52s
Test CUDA support	18s
Test build-std (x86_64-tvos)	5m 28s
Test (stable)	28s
MSRV (ubuntu-latest)	25s
Test (beta)	30s
MSRV (windows-latest)	41s
Test (nightly)	31s
Rustfmt	7s
Test (linux32)	1m 9s
Test (macos)	1m 54s
Test (aarch64-macos)	42s
Test (aarch64-ios)	1m 19s
Test (win32)	1m 16s
Test (win64)	2m 35s
Test (mingw32)	1m 30s
Test (mingw64)	1m 36s
Test (windows-2019)	2m 11s
Test (windows-aarch64, windows-latest, stable, aarch64-pc-windows-msvc, --no-run)	1m 28s
Test (windows-clang, windows-2019, stable, x86_64-pc-windows-msvc, clang, clang++)	1m 50s
Test (windows-clang-cl, windows-2019, stable, x86_64-pc-windows-msvc, clang-cl, clang-cl)	2m 19s
	38m 34s

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