Allow struct, union and enum type declarations to be annotated.

Change-Id: Idce594b47c324d8420638e2e8853da3c99150672
Bug: 31800672
Test: hidl_test, hidl_test_java
diff --git a/Scope.cpp b/Scope.cpp
index c4cc587..be60c95 100644
--- a/Scope.cpp
+++ b/Scope.cpp
@@ -85,6 +85,16 @@
     return false;
 }
 
+bool Scope::containsInterfaces() const {
+    for (const NamedType *type : mTypes) {
+        if (type->isInterface()) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 std::string Scope::pickUniqueAnonymousName() const {
     static size_t sNextID = 0;