Improve stdarch-gen-arm a bit #2413

Job	Run time
Check Style	16s
Build Documentation	1m 17s
Env Override (ubuntu-latest)	15s
Automatic intrinsic verification	27s
Test (i686-unknown-linux-gnu)	1m 55s
Env Override (windows-latest)	23s
Test (x86_64-unknown-linux-gnu)	3m 53s
Build std_detect	58s
Test (x86_64-unknown-linux-gnu-emulated)	10m 52s
Test (arm-unknown-linux-gnueabihf)	1m 22s
Test (armv7-unknown-linux-gnueabihf)	11m 1s
Test (aarch64-unknown-linux-gnu)	21m 0s
Test (riscv64gc-unknown-linux-gnu)	1m 13s
Test (powerpc64le-unknown-linux-gnu)	3m 26s
Test (s390x-unknown-linux-gnu)	1m 24s
Test (wasm32-wasip1)	1m 26s
Test (i586-unknown-linux-gnu)	1m 58s
Test (nvptx64-nvidia-cuda)	24s
Test (thumbv6m-none-eabi)	13s
Test (thumbv7m-none-eabi)	13s
Test (thumbv7em-none-eabi)	13s
Test (thumbv7em-none-eabihf)	13s
Test (loongarch64-unknown-linux-gnu)	1m 32s
Test (x86_64-apple-darwin)	7m 55s
Test (aarch64-apple-darwin)	37s
Test (x86_64-pc-windows-msvc)	6m 49s
Test (i686-pc-windows-msvc)	3m 10s
Test (aarch64-pc-windows-msvc)	1m 25s
Test (x86_64-pc-windows-gnu)	7m 1s
Test (aarch64-apple-ios-macabi, macos-latest, true)	44s
Test (x86_64-apple-ios-macabi, macos-13)	5m 46s
success	1s
	1h 39m 22s

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