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/editors/object/object_shader_fx.c b/source/blender/editors/object/object_shader_fx.c
index 457d2421253..db0c8c54186 100644
--- a/source/blender/editors/object/object_shader_fx.c
+++ b/source/blender/editors/object/object_shader_fx.c
@@ -294,7 +294,7 @@ void OBJECT_OT_shaderfx_add(wmOperatorType *ot)
 static bool edit_shaderfx_poll_generic(bContext *C, StructRNA *rna_type, int obtype_flag)
 {
   PointerRNA ptr = CTX_data_pointer_get_type(C, "shaderfx", rna_type);
-  Object *ob = (ptr.id.data) ? ptr.id.data : ED_object_active_context(C);
+  Object *ob = (ptr.owner_id) ? (Object *)ptr.owner_id : ED_object_active_context(C);
 
   if (!ptr.data) {
     CTX_wm_operator_poll_msg_set(C, "Context missing 'shaderfx'");
@@ -307,7 +307,7 @@ static bool edit_shaderfx_poll_generic(bContext *C, StructRNA *rna_type, int obt
   if (obtype_flag && ((1 << ob->type) & obtype_flag) == 0) {
     return 0;
   }
-  if (ptr.id.data && ID_IS_LINKED(ptr.id.data)) {
+  if (ptr.owner_id && ID_IS_LINKED(ptr.owner_id)) {
     return 0;
   }