Add private helpers needed for job queue.

We need to compare the data in parcels.  Bleah.

Test: not relevant here.

Change-Id: I7b694ec89793449bf7ac342f663dc534feedf9b6
diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index da94305..39bb078 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -553,6 +553,14 @@
     return err;
 }
 
+int Parcel::compareData(const Parcel& other) {
+    size_t size = dataSize();
+    if (size != other.dataSize()) {
+        return size < other.dataSize() ? -1 : 1;
+    }
+    return memcmp(data(), other.data(), size);
+}
+
 bool Parcel::allowFds() const
 {
     return mAllowFds;