Add feature to support platforms without atomic CAS #836

Job	Run time
miri	15m 19s
loom	19s
cross (i686-unknown-linux-gnu, ubuntu-latest)	43s
minrust	2m 16s
cross (armv7-unknown-linux-gnueabihf, ubuntu-22.04-arm)	1m 5s
nightly	1m 25s
cross (powerpc-unknown-linux-gnu, ubuntu-latest)	1m 40s
no-std	16s
cross (powerpc64-unknown-linux-gnu, ubuntu-latest)	1m 30s
panic=abort tests	31s
cross (wasm32-wasip1, ubuntu-latest)	33s
rustfmt	11s
stable (ubuntu-latest)	2m 0s
stable (ubuntu-22.04-arm)	1m 57s
tsan	1m 18s
stable (macos-latest)	1m 47s
stable (windows-latest)	3m 34s
Publish Documentation	11s
	36m 35s

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