Add is*() functions for more types.

Test: compiles
Change-Id: Ibeba6c814ac17192481935a067b7c835c4008dc7
diff --git a/EnumType.h b/EnumType.h
index 6842fc1..e810ed3 100644
--- a/EnumType.h
+++ b/EnumType.h
@@ -133,6 +133,8 @@
 
     std::string typeName() const override;
 
+    bool isBitField() const override;
+
     void addNamedTypesToSet(std::set<const FQName> &set) const override;
 
     bool isCompatibleElementType(Type *elementType) const override;