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_wm_gizmo.c b/source/blender/makesrna/intern/rna_wm_gizmo.c
index 534e3042768..ba26929d808 100644
--- a/source/blender/makesrna/intern/rna_wm_gizmo.c
+++ b/source/blender/makesrna/intern/rna_wm_gizmo.c
@@ -252,7 +252,7 @@ static void rna_Gizmo_update_redraw(Main *UNUSED(bmain), Scene *UNUSED(scene), P
 static wmGizmo *rna_GizmoProperties_find_operator(PointerRNA *ptr)
 {
 #  if 0
-  wmWindowManager *wm = ptr->id.data;
+  wmWindowManager *wm = (wmWindowManager *)ptr->owner_id;
 #  endif
 
   /* We could try workaruond this lookup, but not trivial. */