Rollup merge of #136375 - Zalathar:llvm-di-builder, r=workingjubilee

cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 1)

Part of #134001, follow-up to #136326, extracted from #134009.

This PR performs an arbitrary subset of the LLVM-C binding migrations from #134009, which should make it less tedious to review. The remaining migrations can occur in one or more subsequent PRs.

Author: fmease