Rust

Add `pod_saturating` feature #643

Job	Run time
Test with miri	1m 10s
Test on i686-unknown-linux-gnu with cross	1m 3s
Test Rust 1.34.0 on ubuntu-latest	1m 48s
Test with -Zsanitizer=address	38s
Test Rust stable on ubuntu-latest	16s
Test with -Zsanitizer=memory	40s
Test Rust beta on ubuntu-latest	13s
Test Rust nightly on ubuntu-latest	22s
Test Rust stable on macos-latest	20s
Test Rust stable on windows-latest	27s
Test Rust stable-x86_64-gnu on windows-latest	37s
Test Rust stable-i686-msvc on windows-latest	48s
Test Rust stable-i686-gnu on windows-latest	35s
	8m 57s

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