message: Makefile: add riscv32imac target in setup
  The hifive1 board needs the 'a' atomic operations as well. Install that
  target during setup.
diff: @@ -33,6 +33,7 @@ endif
  .PHONY: setup
  setup:
  rustup target add thumbv7em-none-eabi
  + rustup target add riscv32imac-unknown-none-elf
  rustup target add riscv32imc-unknown-none-elf
  rustup component add rustfmt
  rustup component add clippy
  