loci: add a function to determine whether a class is an inheritance root
diff --git a/c_gen/type_maps.py b/c_gen/type_maps.py
index 69ecd41..abbc2d5 100644
--- a/c_gen/type_maps.py
+++ b/c_gen/type_maps.py
@@ -53,6 +53,9 @@
         return True
     return loxi_globals.unified.class_by_name(cls).virtual
 
+def class_is_inheritance_root(cls):
+    return cls in inheritance_roots
+
 # map from parent class name to set of subclass names
 inheritance_map = dict()