There is an updated pull request by leahneukirchen against master on the void-packages repository

https://github.com/leahneukirchen/void-packages rust-cross
https://github.com/void-linux/void-packages/pull/50016

 New package: rust-cross-1.77.1 
This package adds core libraries for rust to cross-compile to

* 'thumbv6m-none-eabi', for Raspberry Pi Pico
* 'riscv32imc-unknown-none-elf', for ESP-C3
* 'riscv32imac-unknown-none-elf', for ESP-C6
* 'wasm32-unknown-unknown', for WASM

These targets cannot be build in the main template because they conflict with `docs = true`.

Having this package avoids needing to use `rustup` to develop for these platforms.
More target suggestions are welcome.  Each target adds ~40MB of data.

Open questions:

* Package name
* Should this be a split package?

Once the `-Z build-std` (https://github.com/rust-lang/wg-cargo-std-aware) cargo feature becomes available in stable, this package is redundant.

#### Testing the changes
- I tested the changes in this PR: **briefly**


A patch file from https://github.com/void-linux/void-packages/pull/50016.patch is attached