Update POSIX reference URLs to 1003.1-2024. (#1160) #4235

Job	Run time
Rustfmt	13s
Check --no-default-features (nightly)	59s
Check nightly-only targets (nightly)	22s
Check (stable)	6m 22s
Check selected Tier 3 platforms (nightly)	4m 47s
Check (nightly)	6m 20s
Check (1.63)	10m 32s
Test (ubuntu)	43s
Test rustix_use_experimental_asm (powerpc64le-linux)	1m 12s
Test (ubuntu-20.04)	43s
Test use-libc (ubuntu)	42s
Test use-libc (i686-linux)	59s
Test (i686-linux)	1m 10s
Test use-libc (aarch64-linux)	1m 15s
Test use-libc (powerpc64le-linux)	1m 5s
Test (aarch64-linux)	1m 14s
Test use-libc (riscv64-linux)	1m 9s
Test use-libc (arm-linux)	1m 7s
Test (powerpc64le-linux)	1m 4s
Test (riscv64-linux)	1m 4s
Test (s390x-linux)	1m 4s
Test (arm-linux)	1m 6s
Test (ubuntu-stable)	46s
Test (i686-linux-stable)	1m 6s
Test (aarch64-linux-stable)	1m 15s
Test (riscv64-linux-stable)	1m 17s
Test (s390x-linux-stable)	1m 16s
Test (powerpc64le-linux-stable)	1m 5s
Test (arm-linux-stable)	58s
Test (ubuntu-1.63)	2m 31s
Test (i686-linux-1.63)	2m 55s
Test (aarch64-linux-1.63)	3m 9s
Test (riscv64-linux-1.63)	2m 54s
Test (s390x-linux-1.63)	2m 59s
Test (powerpc64le-linux-1.63)	2m 46s
Test (arm-linux-1.63)	3m 4s
Test (macos-latest)	17m 47s
Test (macos-12)	18m 35s
Test (windows)	44s
Test (windows-2019)	45s
Test (musl)	50s
	1h 51m 54s

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