Optimize jobserver `try_acquire` (#1037) #1427

Job	Run time
MSRV (ubuntu-latest)	1m 46s
Test build-std (aarch64-tvos)	5m 31s
Clippy	9s
MSRV (windows-latest)	2m 14s
Test build-std (aarch64-tvos-sim)	6m 11s
Test CUDA support	53s
Test build-std (x86_64-tvos)	5m 32s
Rustfmt	8s
Test (stable)	1m 6s
Test (beta)	1m 17s
Test (nightly)	1m 12s
Test (linux32)	1m 32s
Test (macos)	4m 14s
Test (aarch64-macos)	1m 19s
Test (aarch64-ios)	3m 54s
Test (win32)	2m 54s
Test (win64)	2m 27s
Test (mingw32)	2m 48s
Test (mingw64)	2m 40s
Test (windows-2019)	2m 51s
Test (windows-aarch64, windows-latest, stable, aarch64-pc-windows-msvc, --no-run)	2m 23s
Test (windows-clang, windows-2019, stable, x86_64-pc-windows-msvc, clang, clang++)	3m 49s
Test (windows-clang-cl, windows-2019, stable, x86_64-pc-windows-msvc, clang-cl, clang-cl)	3m 6s
	59m 56s

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