Add support for RISC-V

[chazapis]

The work is part of an ongoing effort to run K3s on RISC-V. In K3s, klipper-lb is part of the default deployment.

The resulting container image is built with ARCH=riscv64 make.

[chazapis]

@matttrach, @galal-hussein, @brandond Sorry to bother you, but it has been over 3 months with no response. This is a really helpful feature that requires no code changes. Could it possibly be included in the next release?

[brandond]

Thanks for the PR. We're not yet committed to building for risc-v. We will need to tackle this at a project level (including deciding on a standard approach to building for this platform, and adding risc-v support to our mirrored images) before we are ready to start building things for risc-v.

[chazapis]

@brandond, I understand. Thank you for the feedback. I just want to stress out that even though the RISC-V community is still small, it is constantly growing. Having this project (and eventually K3s) supporting the architecture would be great! Let me know if there is any way I can help.