Support for a generic "binder" type (reflected as "interface" in hidl)

marshaled as a sp<hwbinder::IBinder>.

Bug: 30884691
Change-Id: I157d78fbbe839637805359441925aec597c52383
diff --git a/Type.cpp b/Type.cpp
index 296aba8..912bc25 100644
--- a/Type.cpp
+++ b/Type.cpp
@@ -26,6 +26,10 @@
     return false;
 }
 
+bool Type::isBinder() const {
+    return false;
+}
+
 const ScalarType *Type::resolveToScalarType() const {
     return NULL;
 }