simplify simd_ty macro: do not repeat the element type N times #1955

Job	Run time
Check Style	13s
Automatic intrinsic verification	26s
Env Override	15s
Build std_detect	56s
Build Documentation	1m 5s
Test (i686-unknown-linux-gnu)	1m 13s
Test (x86_64-unknown-linux-gnu)	1m 12s
Test (x86_64-unknown-linux-gnu-emulated)	1m 11s
Test (arm-unknown-linux-gnueabihf)	1m 11s
Test (armv7-unknown-linux-gnueabihf)	1m 13s
Test (aarch64-unknown-linux-gnu)	57s
Test (riscv64gc-unknown-linux-gnu)	1m 11s
Test (powerpc64le-unknown-linux-gnu)	1m 11s
Test (s390x-unknown-linux-gnu)	1m 11s
Test (wasm32-wasi)	1m 11s
Test (i586-unknown-linux-gnu)	1m 11s
Test (nvptx64-nvidia-cuda)	27s
Test (thumbv6m-none-eabi)	15s
Test (thumbv7m-none-eabi)	13s
Test (thumbv7em-none-eabi)	16s
Test (thumbv7em-none-eabihf)	14s
Test (aarch64-apple-darwin)	1m 8s
Test (x86_64-pc-windows-msvc)	1m 4s
Test (i686-pc-windows-msvc)	1m 5s
Test (x86_64-apple-darwin, macos-11)	1m 7s
success	1s
	21m 37s

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