patch 8.2.0524: Win32: searching for file matches is slow

patch 8.2.0524: Win32: searching for file matches is slow

Problem:    Win32: searching for file matches is slow.
Solution:   Instead of making another round to find any short filename, check
            for the short name right away. Avoid using an ordinary file like a
            directory.  (Nir Lichtman, closes #5883)