Add Default Constructor Required by libstdc++

Test: Build with CMake. See aosp/2629369.
Bug: 285204695
Change-Id: I105552df72fe8b4f15f75192a5c36480c1bdc5c7
diff --git a/libs/binder/include/binder/Parcel.h b/libs/binder/include/binder/Parcel.h
index 45e5ace..b94267c 100644
--- a/libs/binder/include/binder/Parcel.h
+++ b/libs/binder/include/binder/Parcel.h
@@ -1289,6 +1289,7 @@
 
     // Fields only needed when parcelling for "kernel Binder".
     struct KernelFields {
+        KernelFields() {}
         binder_size_t* mObjects = nullptr;
         size_t mObjectsSize = 0;
         size_t mObjectsCapacity = 0;