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

rust 1.48
https://github.com/void-linux/void-packages/pull/27119

Description:
based on @jnbr's changes but updated with custom stuff

notably, we now always use external cargo; this means to cross-build rust itself, you no longer need a cargo package available, similarly for cargo itself

also, all checksums have been updated (i have the bootstrap tarballs ready) and we're bootstrapping using rust 1.48 and cargo 0.49 (since i didn't want to bother with rebuilding them again next time we update)

needs rebuild test on x86, and test if crossbuilds still work (we shouldn't need all archs, one or two should do, like some arm musl and non-musl)