FBX IO: Fix pose bone custom props not being exported.

We want to export editbone props in the 'edit data' NodeAttribute FBX nodes,
and the posebone props in the 'object data' Model FBX nodes...

Reported in T69554.

io_scene_fbx/__init__.py

@@ -21,7 +21,7 @@
 bl_info = {
     "name": "FBX format",
     "author": "Campbell Barton, Bastien Montagne, Jens Restemeier",
-    "version": (4, 18, 1),
+    "version": (4, 19, 0),
     "blender": (2, 81, 6),
     "location": "File > Import-Export",
     "description": "FBX IO meshes, UV's, vertex colors, materials, textures, cameras, lamps and actions",

io_scene_fbx/export_fbx_bin.py

@@ -1686,7 +1686,9 @@ def fbx_data_object_elements(root, ob_obj, scene_data):
 
     # Custom properties.
     if scene_data.settings.use_custom_props:
-        fbx_data_element_custom_properties(props, ob_obj.bdata)
+        # Here we want customprops from the 'pose' bone, not the 'edit' bone...
+        bdata = ob_obj.bdata_pose_bone if ob_obj.is_bone else ob_obj.bdata
+        fbx_data_element_custom_properties(props, bdata)
 
     # Those settings would obviously need to be edited in a complete version of the exporter, may depends on
     # object type, etc.

io_scene_fbx/fbx_utils.py

@@ -1007,6 +1007,12 @@ class ObjectWrapper(metaclass=MetaObjectWrapper):
             return ObjectWrapper(self.bdata.parent, self._ref) or ObjectWrapper(self._ref)
     parent = property(get_parent)
 
+    def get_bdata_pose_bone(self):
+        if self._tag == 'BO':
+            return self._ref.pose.bones[self.bdata.name]
+        return None
+    bdata_pose_bone = property(get_bdata_pose_bone)
+
     def get_matrix_local(self):
         if self._tag == 'OB':
             return self.bdata.matrix_local.copy()