message: Adjust discrete_fourier_transform example for OpenCV 3.2
diff: @@ -12,7 +12,7 @@ use opencv::{
  fn main() -> opencv::Result<()> {
  #![allow(non_snake_case)]
  let filename = env::args().skip(1).next().expect("Must supply image filename");
  - let I = imgcodecs::imread(&core::find_file(&filename, true, false)?, imgcodecs::IMREAD_GRAYSCALE)?;
  + let I = imgcodecs::imread(&filename, imgcodecs::IMREAD_GRAYSCALE)?;
  if I.empty()? {
  panic!("Error opening image: {}", filename);
  }
  