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/RNA_access.h b/source/blender/makesrna/RNA_access.h
index 95ea5d75c9f..f03aacf8dbd 100644
--- a/source/blender/makesrna/RNA_access.h
+++ b/source/blender/makesrna/RNA_access.h
@@ -1411,8 +1411,8 @@ StructRNA *ID_code_to_RNA_type(short idcode);
 #define RNA_POINTER_INVALIDATE(ptr) \
   { \
     /* this is checked for validity */ \
-    (ptr)->type = /* should not be needed but prevent bad pointer access, just in case */ \
-        (ptr)->id.data = NULL; \
+    (ptr)->type = NULL; /* should not be needed but prevent bad pointer access, just in case */ \
+    (ptr)->owner_id = NULL; \
   } \
   (void)0