libbinder_ndk: allow disabling interface token

For compatibility with Java interfaces which don't use interface tokens.

Test: CtsNdkBinderTestCases
Bug: 188022639
Change-Id: I77642427993f37971b4b5b5928fc4a3688f17e42
diff --git a/libs/binder/ndk/ibinder_internal.h b/libs/binder/ndk/ibinder_internal.h
index f2c69b3..6509545 100644
--- a/libs/binder/ndk/ibinder_internal.h
+++ b/libs/binder/ndk/ibinder_internal.h
@@ -116,6 +116,9 @@
     const ::android::String16& getInterfaceDescriptor() const { return mWideInterfaceDescriptor; }
     const char* getInterfaceDescriptorUtf8() const { return mInterfaceDescriptor.c_str(); }
 
+    // whether a transaction header should be written
+    bool writeHeader = true;
+
     // required to be non-null, implemented for every class
     const AIBinder_Class_onCreate onCreate;
     const AIBinder_Class_onDestroy onDestroy;