The CLINT is implemented both on the fe310-g002 chip and in the sifive_e
QEMU machine type. Therefore, use that peripheral for consistency.
The only difference is the clock speed, which runs at 10MHz in QEMU for
some reason instead of 32.768kHz as on the physical HiFive1 boards.
QEMU doesn't support the RTC peripheral yet so work around it for now.
This makes the following command work:
tinygo run -target=hifive1-qemu ./testdata/coroutines.go