Function zvariant::serialized_size_fds

pub fn serialized_size_fds<B, T: ?Sized>(
    ctxt: EncodingContext<B>, 
    value: &T
) -> Result<(usize, usize)> where
    B: ByteOrder,
    T: Serialize + Type, 

Calculate the serialized size of T that (potentially) contains FDs.

Returns the serialized size of T and the number of FDs.