@Override
    public void writeSInt32(int fieldNumber, int value, boolean repeated) throws IOException
    {
        buffer.writeVarInt32(makeTag(fieldNumber, WIRETYPE_VARINT));
        buffer.writeVarInt32(encodeZigZag32(value));
    }
Output that differs from the standard by attempting to avoid extra copies of large ByteBuffer fields. When used with
ByteBuffer=true compiler option, we can splice in ByteBuffer objects without copying them. Most of the magic lives in
LinkBuffer, so this class exists just to serialize to a LinkBuffer.

@author Ryan Rawson
protostuff-core/src/main/java/io/protostuff/LowCopyProtobufOutput.java