Add RISC-V 64-bit support and builds

[MichaIng]

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What does this PR aim to accomplish?:

Adds support for RISC-V 64-bit architecture and FTL builds to CI.

How does this PR accomplish the above?:

• Added struct_size detection according to RISC-V C API: https://github.com/riscv-non-isa/riscv-c-api-doc/blob/master/riscv-c-api.md#preprocessor-definitions
• Added binary test
• Added build to GitHub Actions workflow
• Add Pi-hole riscv64 Docker base image: Add RISC-V 64-bit container builds docker-base-images#63
  Tests/builds cannot be done since GitHub secrets are not available in actions from forks. Not sure how to unblock best.

Companion PRs:

• Add RISC-V 64-bit container builds docker-base-images#63
• Add support for RISC-V 64-bit installs pi-hole#5196

Link documentation PRs if any are needed to support this PR:

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[pralor-bot]

This pull request has been mentioned on Pi-hole Userspace. There might be relevant details there:

https://discourse.pi-hole.net/t/ftl-risc-v-builds-support/61629/7

[DL6ER]

@MichaIng ghcr.io/pi-hole/ftl-build:v1.26-riscv64 is now available. I also have a PR to avoid the ❌ on the spell-check action but this hasn't landed in devlopment yet.

[DL6ER]

@MichaIng You'll have to update the containers from v1.23 to v1.26 in .github/workflows/build.yml:

[MichaIng]

Ah, make sense.

Now I see those %ssudo and %sstart. Feels like the very same as on our docs and website repos: Spell checking is generally great, but one has to maintain a huge exclusion/word list 😄. I was not brave enough to implement it in DietPi main repo, yet 🙈. EDIT: Although codespell seems to do a very good job in code OOTB, better than aspell on filtered HTML.

[DL6ER]

Should be fixed in development but but I'm happy to overwrite code-spell here. Thanks for your PR!

[pralor-bot]

This pull request has been mentioned on Pi-hole Userspace. There might be relevant details there:

https://discourse.pi-hole.net/t/pi-hole-ftl-v5-22-web-v5-19-and-core-v5-16-1-released/61999/1