There's a merged pull request on the void-packages repository

sdcc: enable cross and add nonfree build option.
https://github.com/void-linux/void-packages/pull/22784

Description:
- Enabling cross is done by disabling building the device libraries
during packaging.
- Some PIC headers and files are nonfree, so they shouldn't be
included in the free version.
- Add gc-devel for better memory behavior.

So, it doesn't automatically build a device lib if it needs one, which means it's a bit useless in this state (I think). Should we ship it in this state? The example I've found online for cross compiling uses the native builder to create the libraries and then copies that over.

https://github.com/ekawahyu/sdcc-CC2530/blob/master/sdcc-build-for-windows-from-osx.sh