'if exists' takes a parameter which can be directory, directory\ or
directory\. for example, and should equate to true if the directory
exists. The syntax directory\ is explicitly rejected by FindFirstFile
and hence was not working - look for this specific case, and if found
append a '.'.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=45506Signed-off-by: Jason Edmeades <us@edmeades.me.uk>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>