Aligning native Parcel implementation to Java.

The Java implementation of writing the RPC response header
calculates the length of the header including the 4 bytes
specifying the header length but the native implementation
excludes the 4 bytes specifying the length from the header
length.
The native implementation has been aligned to the Java impl.

Change-Id: I325bf272a63152d8fded4cf4e51a906b5a9bfe19