Fix #107946: Blender crashes when relocating a library to another library that uses the same "2nd-level" library.

The issue here is that the `parent` pointer of indirectly linked
libraries would not be propoerly cleared when their current parent was
deleted.

Note that this fix will leave effectively indirectly linked libraries
shown as directly used ones in the UI, until the blendfile is saved and
reloaded. This is not a new issue though, deleting a parent library in
the Outliner has the same effect.

source/blender/blenkernel/intern/blendfile_link_append.cc

@@ -1894,7 +1894,7 @@ void BKE_blendfile_library_relocate(BlendfileLinkAppendContext *lapp_context,
     if (lib->id.tag & LIB_TAG_DOIT) {
       id_us_clear_real(&lib->id);
       if (lib->id.us == 0) {
-        BKE_id_free(bmain, (ID *)lib);
+        BKE_id_delete(bmain, lib);
       }
     }
   }