Remove naked_functions feature usage for x86 (#722) #4379

Job	Run time
Check nightly-only targets (nightly)	21s
Check --no-default-features (nightly)	44s
Check (stable)	3m 15s
Check selected Tier 3 platforms (nightly)	2m 19s
Check (nightly)	3m 21s
Check (1.48)	6m 55s
Rustfmt	16s
Test rustix_use_experimental_asm (powerpc64le-linux)	55s
Test (ubuntu)	31s
Test use-libc (ubuntu)	27s
Test (ubuntu-20.04)	31s
Test use-libc (i686-linux)	53s
Test (i686-linux)	1m 34s
Test use-libc (aarch64-linux)	1m 9s
Test (aarch64-linux)	59s
Test use-libc (powerpc64le-linux)	59s
Test (powerpc64le-linux)	1m 6s
Test use-libc (riscv64-linux)	55s
Test (riscv64-linux)	1m 9s
Test use-libc (arm-linux)	1m 17s
Test (s390x-linux)	4m 8s
Test (arm-linux)	2m 10s
Test (ubuntu-stable)	34s
Test (ubuntu-1.48)	1m 53s
Test (i686-linux-stable)	1m 21s
Test (aarch64-linux-stable)	1m 0s
Test (riscv64-linux-stable)	1m 21s
Test (s390x-linux-stable)	1m 58s
Test (powerpc64le-linux-stable)	59s
Test (arm-linux-stable)	4m 21s
Test (ubuntu-1.48)	2m 0s
Test (i686-linux-1.48)	2m 47s
Test (aarch64-linux-1.48)	2m 7s
Test (riscv64-linux-1.48)	2m 4s
Test (s390x-linux-1.48)	3m 16s
Test (powerpc64le-linux-1.48)	2m 18s
Test (arm-linux-1.48)	3m 44s
Test (macos-latest)	34s
Test (macos-11)	1s
Test (windows)	44s
Test (windows-2019)	58s
	1h 9m 54s

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