Fix Windows build error.
Fix Windows build error.

BitFunnel/BitFunnel,BitFunnel/BitFunnel,danluu/BitFunnel,BitFunnel/BitFunnel,danluu/BitFunnel,BitFunnel/BitFunnel,danluu/BitFunnel,BitFunnel/BitFunnel,danluu/BitFunnel,danluu/BitFunnel,BitFunnel/BitFunnel,danluu/BitFunnel