Rust

Support `-Zbuild-std` #686

Job	Run time
check rustfmt	9s
tests (ubuntu-latest, x86_64-unknown-linux-gnu)	2m 50s
check clippy	26s
nightly-integration (ubuntu-latest, x86_64-unknown-linux-gnu)	3m 7s
tests (macos-latest, x86_64-apple-darwin)	2m 25s
nightly-integration (macos-latest, x86_64-apple-darwin)	2m 52s
tests (windows-latest, i686-pc-windows-msvc)	3m 5s
nightly-integration (windows-latest, i686-pc-windows-msvc)	3m 8s
	18m 2s

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