Blender Git Loki

Fix access to invalid data in Outliner tree building

Non-ID tree-elements would cast their data pointer to `ID *` and take the name
and ID-Code from there. The name would actually be overridden a few lines
later, so that didn't cause issues. But the ID-Code stored inside the tree
element kept an undefined value. In practice that probably didn't cause many
issues either, since it's just an undefined value that was very unlikely to
take a valid 16-bit ID-code value, meaning ID-Code checks would simply fail as
they should. Further there typically are other checks to see if the element
actually represents an ID.
However, in theory this may have caused a few random crashes or
data-corruptions.