Mesh: Move runtime data out of DNA

This commit replaces the `Mesh_Runtime` struct embedded in `Mesh`
with `blender::bke::MeshRuntime`. This has quite a few benefits:
- It's possible to use C++ types like `std::mutex`, `Array`,
  `BitVector`, etc. more easily
- Meshes saved in files are slightly smaller
- Copying and writing meshes is a bit more obvious without
  clearing of runtime data, etc.

The first is by far the most important. It will allows us to avoid a
bunch of manual memory management boilerplate that is error-prone and
annoying. It should also simplify future CoW improvements for runtime
data.

This patch doesn't change anything besides changing `mesh.runtime.data`
to `mesh.runtime->data`. The cleanups above will happen separately.

Differential Revision: https://developer.blender.org/D16180

1 files changed, 1 insertions, 1 deletions

diff --git a/source/blender/modifiers/intern/MOD_weighted_normal.cc b/source/blender/modifiers/intern/MOD_weighted_normal.cc
index 6e3961bef64..1ebd5423d39 100644
--- a/source/blender/modifiers/intern/MOD_weighted_normal.cc
+++ b/source/blender/modifiers/intern/MOD_weighted_normal.cc
@@ -676,7 +676,7 @@ static Mesh *modifyMesh(ModifierData *md, const ModifierEvalContext *ctx, Mesh *
   MEM_SAFE_FREE(wn_data.mode_pair);
   MEM_SAFE_FREE(wn_data.items_data);
 
-  result->runtime.is_original_bmesh = false;
+  result->runtime->is_original_bmesh = false;
 
   return result;
 }