Add getHashChain() to IBase.

Each interface has a getHashChain() method that
returns the hash of all .hal files from the rtti
of the interface up to IBase.

Test: hidl_test

Bug: 36602587
Change-Id: I13f2e54bd45593c70064dff05fa934d5cd01996a
diff --git a/ArrayType.h b/ArrayType.h
index ae58d28..3bb091f 100644
--- a/ArrayType.h
+++ b/ArrayType.h
@@ -44,6 +44,8 @@
     std::string getCppType(StorageMode mode,
                            bool specifyNamespaces) const override;
 
+    std::string getInternalDataCppType() const;
+
     void addNamedTypesToSet(std::set<const FQName> &set) const override;
 
     std::string getJavaType(bool forInitializer) const override;