Highgui window is not scaled properly when displaying small images (Bug #3906)

In OpenCV 3.0 (I did not try other versions), when displaying small images, even with the `WINDOW_AUTOSIZE` flag, the window is not scaled properly.

    #include <opencv2/core.hpp>
    #include <opencv2/imgcodecs.hpp>
    #include <opencv2/highgui.hpp>
    #include <iostream>

    using namespace cv;
    using namespace std;

    int main( int argc, char** argv )
    {
        if( argc != 2)
        {
         cout <<" Usage: display_image ImageToLoadAndDisplay" << endl;
         return -1;
        }

        Mat image;
        image = imread(argv[1], IMREAD_COLOR); // Read the file

        if( image.empty() )                      // Check for invalid input
        {
            cout <<  "Could not open or find the image" << std::endl ;
            return -1;
        }

        namedWindow( "Display window", WINDOW_AUTOSIZE ); // Create a window for display.
        imshow( "Display window", image );                // Show our image inside it.

        while (waitKey(0) != 27); // Wait for ESC key
        return 0;
    }

Test image (100x100):

Results:

When moving the mouse to the displayed image, I got this: