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, 1 insertions, 1 deletions

diff --git a/source/blender/makesrna/intern/rna_workspace.c b/source/blender/makesrna/intern/rna_workspace.c
index 6349b5206d6..47138653af1 100644
--- a/source/blender/makesrna/intern/rna_workspace.c
+++ b/source/blender/makesrna/intern/rna_workspace.c
@@ -58,7 +58,7 @@ static void rna_window_update_all(Main *UNUSED(bmain),
 
 void rna_workspace_screens_begin(CollectionPropertyIterator *iter, PointerRNA *ptr)
 {
-  WorkSpace *workspace = ptr->id.data;
+  WorkSpace *workspace = (WorkSpace *)ptr->owner_id;
   rna_iterator_listbase_begin(iter, BKE_workspace_layouts_get(workspace), NULL);
 }