RNA: Cleanup PointerRNA struct

The old layout of `PointerRNA` was confusing for historic reasons:
```
typedef struct PointerRNA {
  struct {
    void *data;
  } id;

  struct StructRNA *type;
  void *data;
} PointerRNA;
```

This patch updates it to:
```
typedef struct PointerRNA {
  struct ID *owner_id;
  struct StructRNA *type;
  void *data;
} PointerRNA;
```

Throughout the code base `id.data` was replaced with `owner_id`.
Furthermore, many explicit pointer type casts were added which
were implicit before. Some type casts to `ID *` were removed.

Reviewers: brecht, campbellbarton

Differential Revision: https://developer.blender.org/D5558

1 files changed, 2 insertions, 2 deletions

diff --git a/source/blender/makesrna/intern/rna_context.c b/source/blender/makesrna/intern/rna_context.c
index 735cd1fd923..579dd92b703 100644
--- a/source/blender/makesrna/intern/rna_context.c
+++ b/source/blender/makesrna/intern/rna_context.c
@@ -178,14 +178,14 @@ static PointerRNA rna_Context_collection_get(PointerRNA *ptr)
 static PointerRNA rna_Context_layer_collection_get(PointerRNA *ptr)
 {
   bContext *C = (bContext *)ptr->data;
-  ptr->id.data = CTX_data_scene(C);
+  ptr->owner_id = &CTX_data_scene(C)->id;
   return rna_pointer_inherit_refine(ptr, &RNA_LayerCollection, CTX_data_layer_collection(C));
 }
 
 static PointerRNA rna_Context_tool_settings_get(PointerRNA *ptr)
 {
   bContext *C = (bContext *)ptr->data;
-  ptr->id.data = CTX_data_scene(C);
+  ptr->owner_id = &CTX_data_scene(C)->id;
   return rna_pointer_inherit_refine(ptr, &RNA_ToolSettings, CTX_data_tool_settings(C));
 }