Remove most linux-raw-sys types from the public API #4621

Job	Run time
Rustfmt	6s
Check (stable)	6m 27s
Check --no-default-features (nightly)	53s
Check nightly-only targets (nightly)	21s
Check (nightly)	6m 8s
Check selected Tier 3 platforms (nightly)	4m 43s
Check (1.63)	9m 54s
Test rustix_use_experimental_asm (powerpc64le-linux)	1m 20s
Test rustix_use_experimental_asm (s390x-linux)	2m 9s
Test use-libc (ubuntu)	44s
Test use-libc (i686-linux)	1m 10s
Test (ubuntu)	43s
Test use-libc (aarch64-linux)	1m 25s
Test (ubuntu-20.04)	41s
Test use-libc (powerpc64le-linux)	1m 21s
Test (i686-linux)	1m 8s
Test use-libc (riscv64-linux)	1m 22s
Test (aarch64-linux)	1m 16s
Test use-libc (s390x-linux)	1m 20s
Test (powerpc64le-linux)	1m 14s
Test use-libc (arm-linux)	2m 27s
Test (riscv64-linux)	1m 10s
Test (s390x-linux)	1m 15s
Test (arm-linux)	1m 8s
Test (ubuntu-stable)	44s
Test (i686-linux-stable)	1m 14s
Test (aarch64-linux-stable)	1m 15s
Test (riscv64-linux-stable)	1m 16s
Test (s390x-linux-stable)	1m 18s
Test (powerpc64le-linux-stable)	1m 16s
Test (arm-linux-stable)	1m 5s
Test (ubuntu-1.63)	2m 25s
Test (i686-linux-1.63)	2m 48s
Test (aarch64-linux-1.63)	3m 1s
Test (riscv64-linux-1.63)	2m 50s
Test (s390x-linux-1.63)	2m 50s
Test (powerpc64le-linux-1.63)	2m 53s
Test (arm-linux-1.63)	3m 9s
Test (macos-latest)	37s
Test (macos-13)	59s
Test (windows)	59s
Test (windows-2019)	1m 7s
Test (musl)	48s
	1h 22m 59s

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