arch.h: Add RISC-V support

4 jobs for riscv in 2 minutes and 46 seconds (queued for 1 second)
Status Job ID Name Coverage
  Container
passed #10975867
aarch64
build-container-aarch64

00:01:33

passed #10975866
build-container-x86_64

00:00:21

 
  Build
passed #10975869
aarch64
build-aarch64

00:00:43

passed #10975868
build-x86_64

00:01:12