Request: support for `riscv64-unknown-linux-musl`

[walksanatora]

Checklist

• I've looked through the issues and pull requests for similar request
• This feature could be solved with a custom docker image (optional)

Describe your request

Simply support for riscv64-unknown-linux-musl when cross compiling
I tried to make my own docker image by modifying the aarch64 musl image, but i could not get it right

Describe why this would be a good inclusion for cross

some systems use systems like alpine use musl and alpine is used as the basis for many lightweight/embeded llinux and riscv is a small architecture so it (appears to be) easy to emulate
support for riscv64 musl would be very nice for cross compiling (it is also a rust target)

[Coekjan]

Rust 1.82 Promote riscv64gc-unknown-linux-musl to tier 2. Any progress on this issue?

[karalabe]

It doens't seem to work though:

curl -sSf https://sh.rustup.rs | sh -s -- --profile minimal -y

curl: (22) The requested URL returned error: 404
rustup: installer for platform 'riscv64gc-unknown-linux-musl' not found, this may be unsupported

[Emilgardis]

@karalabe that's related to host tools, we only need target to work, so not an issue