Rust

A bit of cleanup. #329

Job	Run time
test (nasm, x86_64-unknown-linux-gnu)	1m 44s
test (nasm, armv7-unknown-linux-gnueabihf)	1m 47s
test (nasm, i686-pc-windows-msvc)	2m 40s
test (no-nasm, i686-unknown-linux-gnu)	1m 19s
test (nasm, x86_64-pc-windows-msvc)	2m 22s
test (no-nasm, i686-pc-windows-msvc)	3m 0s
test (no-nasm, armv7-unknown-linux-gnueabihf)	1m 23s
test (nasm, aarch64-pc-windows-msvc)	2m 39s
test (nasm, aarch64-apple-darwin)	1m 25s
test (nasm, i686-unknown-linux-gnu)	1m 41s
test (no-nasm, aarch64-apple-darwin)	1m 5s
test (no-nasm, x86_64-pc-windows-msvc)	2m 52s
test (no-nasm, x86_64-unknown-linux-gnu)	1m 24s
test (no-nasm, aarch64-pc-windows-msvc)	2m 28s
test (aarch64-unknown-linux-gnu, ubuntu-latest, gcc-aarch64-linux-gnu g++-aarch64-linux-gnu)	1m 26s
	29m 15s

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