Integrate RISC-V support #11

Job	Run time
build-native-gcc	3m 3s
build-native-llvm	3m 21s
test-native-gcc	9m 28s
build-aarch64-gcc	7m 36s
test-native-llvm	7m 12s
build-aarch64-llvm	3m 51s
build-armhf-gcc	4m 18s
build-armhf-llvm	4m 14s
build-ppc64el-gcc	3m 56s
build-ppc64el-llvm	3m 33s
build-s390x-gcc	2m 55s
build-s390x-llvm	3m 10s
build-riscv64-llvm	1m 33s
test-aarch64-gcc (qemu_cpu: "max,sve=off")	15m 34s
test-aarch64-gcc (qemu_cpu: "max,sve=on,sve128=on")	22m 2s
test-aarch64-gcc (qemu_cpu: "max,sve=on,sve256=on")	17m 52s
test-aarch64-gcc (qemu_cpu: "max,sve=on,sve512=on")	17m 5s
test-armhf-gcc (qemu_cpu: "max")	6m 26s
test-armhf-llvm (qemu_cpu: "max")	5m 31s
test-ppc64el-gcc (qemu_cpu: "power10")	15m 38s
test-ppc64el-llvm (qemu_cpu: "power10")	16m 8s
test-s390x-gcc (qemu_cpu: "")	10m 38s
test-s390x-llvm (qemu_cpu: "")	12m 4s
test-riscv64-llvm (qemu_cpu: "rv64,zba=true,zbb=true,zbs=true,v=false")	4m 39s
test-riscv64-llvm (qemu_cpu: "rv64,zba=true,zbb=true,zbs=true,v=true,vlen=128,elen=64,vext_spec=v1.0")	6m 22s
test-riscv64-llvm (qemu_cpu: "rv64,zba=true,zbb=true,zbs=true,v=true,vlen=256,elen=64,vext_spec=v1.0")	9m 55s
test-riscv64-llvm (qemu_cpu: "rv64,zba=true,zbb=true,zbs=true,v=true,vlen=512,elen=64,vext_spec=v1.0")	7m 23s
	3h 45m 27s

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