Added `Counter<u32, AtomicU32>` implementation #710

Job	Run time
Clippy	1m 16s
Check	1m 33s
Cross compile (armv7-unknown-linux-gnueabihf)	9s
Check rustdoc intra-doc links	42s
Cross compile (powerpc-unknown-linux-gnu)	11s
Rustfmt	19s
Cross compile (powerpc64-unknown-linux-gnu)	19s
Test Suite	1m 24s
Cross compile (wasm32-unknown-unknown)	10s
	6m 3s

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