Update buildroot to 2024.02

[tianon]

My favorite thing about this is that only the uclibc variants actually change, which tells us that none of the files we take from buildroot in the other variants have changed (which has caused unexpected breakage in the past). 😄

[tianon]

Huh, arguably this should actually drop all the other architectures metadata for the builds that change, but it's hard to know which ones change and that delete/re-add would kill the "nice metadata history" property I'm going for by merging them to master in the first place. 🤔

[tianon]

I guess we really should probably do the double build so that we merge all the metadata back in and have all the arch-specific build commits point to a history that has all the metadata merged (and hope that we do them back-to-back enough that we still have hot build cache, or explicitly rebase them 😞).

[tianon]

For now, I think my stance is going to be that if you want accurate/consistent metadata for a specific architecture, you have to look at the build/"dist" branch for that architecture (or master, post-cherry-picks), as every other architecture's branch might / will likely have out-of-date metadata for other architectures. I think that's a fair constraint.