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

2 files changed, 2 insertions, 2 deletions

diff --git a/source/blender/nodes/composite/nodes/node_composite_outputFile.c b/source/blender/nodes/composite/nodes/node_composite_outputFile.c
index faf9e20da51..af806a37341 100644
--- a/source/blender/nodes/composite/nodes/node_composite_outputFile.c
+++ b/source/blender/nodes/composite/nodes/node_composite_outputFile.c
@@ -191,7 +191,7 @@ void ntreeCompositOutputFileSetLayer(bNode *node, bNodeSocket *sock, const char
 static void init_output_file(const bContext *C, PointerRNA *ptr)
 {
   Scene *scene = CTX_data_scene(C);
-  bNodeTree *ntree = ptr->id.data;
+  bNodeTree *ntree = (bNodeTree *)ptr->owner_id;
   bNode *node = ptr->data;
   NodeImageMultiFile *nimf = MEM_callocN(sizeof(NodeImageMultiFile), "node image multi file");
   ImageFormatData *format = NULL;
diff --git a/source/blender/nodes/composite/nodes/node_composite_switchview.c b/source/blender/nodes/composite/nodes/node_composite_switchview.c
index 92e06307afb..cecd8204f4a 100644
--- a/source/blender/nodes/composite/nodes/node_composite_switchview.c
+++ b/source/blender/nodes/composite/nodes/node_composite_switchview.c
@@ -116,7 +116,7 @@ static void cmp_node_switch_view_update(bNodeTree *ntree, bNode *node)
 static void init_switch_view(const bContext *C, PointerRNA *ptr)
 {
   Scene *scene = CTX_data_scene(C);
-  bNodeTree *ntree = ptr->id.data;
+  bNodeTree *ntree = (bNodeTree *)ptr->owner_id;
   bNode *node = ptr->data;
   SceneRenderView *srv;
   bNodeSocket *sock;