Enable ccache on riscv64

[luhenry]

Overview

This is made possible with ggml-org/ccache-action#1

Additional information

Requirements

• I have read and agree with the contributing guidelines
• AI usage disclosure:

[luhenry]

cc @CISC @taronaeo

[CISC]

Unsure how we'll proceed, I think maybe wait for upstream to not pull in additional binaries...

[luhenry]

It’s working, without the binary from riseproject-dev/ccache. https://github.com/riseproject-dev/llama.cpp/actions/runs/24143385497/job/70475993840

[ggerganov]

https://github.com/ggml-org/ccache-action/tree/riscv64 is merged now.

[CISC]

@ggerganov I think this PR is fine to merge as-is, it targets a commit based off 1.2.21 instead of current unreleased main branch.

[luhenry]

Let me bump to hendrikmuhs/ccache-action@480829a for riscv64, unless you want to add a tag?

[CISC]

Let me bump to hendrikmuhs/ccache-action@480829a for riscv64, unless you want to add a tag?

I'd rather not target intermediate changes, best keep it as close as possible to all the other CIs.

[luhenry]

I’ll work on unifying Ubuntu-cpu-riscv64 into the matrix of other Ubuntu-cpu jobs next, making sure there are all the same dependencies as other platforms out of the box