Implement RISC-V Zk intrinsics #1805

Job	Run time
Check Style	26s
Env Override	20s
Automatic intrinsic verification	47s
Build Documentation	1m 30s
Build std_detect	1m 30s
Test (i686-unknown-linux-gnu)	1m 23s
Test (x86_64-unknown-linux-gnu)	1m 19s
Test (x86_64-unknown-linux-gnu-emulated)	1m 20s
Test (arm-unknown-linux-gnueabihf)	1m 23s
Test (armv7-unknown-linux-gnueabihf)	1m 23s
Test (aarch64-unknown-linux-gnu)	1m 23s
Test (riscv64gc-unknown-linux-gnu)	1m 5s
Test (powerpc64le-unknown-linux-gnu)	1m 22s
Test (s390x-unknown-linux-gnu)	1m 21s
Test (wasm32-wasi)	1m 19s
Test (i586-unknown-linux-gnu)	1m 24s
Test (nvptx64-nvidia-cuda)	39s
Test (thumbv6m-none-eabi)	21s
Test (thumbv7m-none-eabi)	20s
Test (thumbv7em-none-eabi)	26s
Test (thumbv7em-none-eabihf)	22s
Test (aarch64-apple-darwin)	1m 17s
Test (x86_64-pc-windows-msvc)	1m 15s
Test (i686-pc-windows-msvc)	1m 16s
Test (x86_64-apple-darwin, macos-11)	1m 17s
	26m 28s

Provide feedback