Fixes needed by io_uring. #3420

Job	Run time
Check --no-default-features (nightly)	1m 15s
Check selected Tier 3 platforms (nightly)	4m 18s
Check nightly-only targets (nightly)	39s
Check (stable)	8m 6s
Check (nightly)	7m 52s
Rustfmt	15s
Check (1.63)	19m 1s
Test rustix_use_experimental_asm (powerpc64le-linux)	1m 47s
Test use-libc (ubuntu)	1m 8s
Test (ubuntu)	1m 3s
Test use-libc (i686-linux)	1m 39s
Test (ubuntu-20.04)	1m 2s
Test use-libc (aarch64-linux)	2m 4s
Test (i686-linux)	1m 31s
Test use-libc (powerpc64le-linux)	1m 32s
Test (aarch64-linux)	1m 34s
Test use-libc (riscv64-linux)	1m 45s
Test use-libc (arm-linux)	1m 32s
Test (powerpc64le-linux)	1m 40s
Test (riscv64-linux)	1m 27s
Test (s390x-linux)	2m 9s
Test (arm-linux)	1m 34s
Test (ubuntu-stable)	1m 6s
Test (i686-linux-stable)	1m 41s
Test (aarch64-linux-stable)	1m 55s
Test (riscv64-linux-stable)	1m 28s
Test (s390x-linux-stable)	1m 32s
Test (powerpc64le-linux-stable)	1m 36s
Test (arm-linux-stable)	1m 52s
Test (ubuntu-1.63)	4m 48s
Test (i686-linux-1.63)	5m 27s
Test (aarch64-linux-1.63)	5m 34s
Test (riscv64-linux-1.63)	5m 11s
Test (s390x-linux-1.63)	5m 16s
Test (powerpc64le-linux-1.63)	5m 28s
Test (arm-linux-1.63)	5m 11s
Test (macos-latest)	1m 55s
Test (macos-11)	1m 21s
Test (windows)	1m 24s
Test (windows-2019)	1m 7s
	1h 58m 45s

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