dbb81ca483
This replaces a `GHash` with `Map<blender::StringRefNull, BHead *>` which simplifies using the type. Additionally, this patch also removes `USE_GHASH_BHEAD` which not seem like it's worth having it nowadays (it was always enabled anyway and I have never seen anyone disable it). Pull Request: https://projects.blender.org/blender/blender/pulls/133057