add support for riscv64
I'm not quite sure if it makes sense to build on riscv64 but I can confirm that it can be built on real riscv64 hardware successfully. So feel free to close it or let me know if there are any issues. thanks.
I'm not quite sure if it makes sense to build on riscv64 but I can confirm that it can be built on real riscv64 hardware successfully. So feel free to close it or let me know if there are any issues. thanks.