RISC-V Support?

Current status maintained in [this comment](https://github.com/conda-forge/conda-forge.github.io/issues/1744#issuecomment-4206395592) by @luhenry

_Previously:_

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### Your question:

I'd like to start a discussion about adding limited support for RISC-V architectures. I'm in the process of helping some colleagues at UC Berkeley transition to using conda-forge instead of system packages for https://fires.im/ and https://chipyard.readthedocs.io/en/stable/. We've transitioned the system yum and pip packages to using conda-forge. The next steps are:
1. to create packages for other x86 things we currently build from source (e.g. [libdwarf](https://github.com/conda-forge/staged-recipes/pull/18638) and [QEMU](https://github.com/conda-forge/staged-recipes/pull/18402))
2. migrate pre-compiled toolchain install https://chipyard.readthedocs.io/en/stable/Chipyard-Basics/Initial-Repo-Setup.html#building-a-toolchain (`--ec2-fast`) to using conda instead of the current tarball extraction technique that is limited in it's portability and has no infrastructure to help in it's maintenance.

Adding the toolchain makes me wonder -- does it make sense to start adding RISC-V architectures to conda-forge? For starters, centos does not support it yet (Fedora does). The current use model builds and installs https://github.com/riscv-collab/riscv-gnu-toolchain into a `$RISCV` prefix (many scripts use the `RISCV` environment variable) and then installs more RISC-V ABI software into that same prefix. I assume that conda-forge would want the cross-toolchain to be installed into a `linux-64` "build prefix" and the subsequent software installed into a prefix that is architecture-specific (for the sake of simplicity, I'm only considering `linux-rv64gc` for now because there are many pieces and options when it comes to RISC-V isa). Come to think of it, we may just want to call it `linux-rv64` and not have more details of which ISA pieces are actually supported encoded in the platform name.

Regardless of whether @conda-forge/core is interested in adding RISC-V platforms, to be able to upload to a new platform type on anaconda.org, we would need to get support for it from Anaconda, right? How does that work when conda-forge supports a platform that upstream Anaconda doesn't? (e.g. `linux-aarch64`)