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/editors/space_action/action_data.c b/source/blender/editors/space_action/action_data.c
index bc7f8a0f79d..5ceaefd6309 100644
--- a/source/blender/editors/space_action/action_data.c
+++ b/source/blender/editors/space_action/action_data.c
@@ -220,7 +220,7 @@ static int action_new_exec(bContext *C, wmOperator *UNUSED(op))
     PointerRNA oldptr;
 
     oldptr = RNA_property_pointer_get(&ptr, prop);
-    oldact = (bAction *)oldptr.id.data;
+    oldact = (bAction *)oldptr.owner_id;
 
     /* stash the old action to prevent it from being lost */
     if (ptr.type == &RNA_AnimData) {
diff --git a/source/blender/editors/space_action/space_action.c b/source/blender/editors/space_action/space_action.c
index 3c879b03126..1685852dd02 100644
--- a/source/blender/editors/space_action/space_action.c
+++ b/source/blender/editors/space_action/space_action.c
@@ -373,7 +373,7 @@ static void saction_channel_region_message_subscribe(const struct bContext *UNUS
    * so just whitelist the entire structs for updates
    */
   {
-    wmMsgParams_RNA msg_key_params = {{{0}}};
+    wmMsgParams_RNA msg_key_params = {{0}};
     StructRNA *type_array[] = {
         &RNA_DopeSheet, /* dopesheet filters */