ui/cocoa.m: Add support for cdr files

Allow the user to select .cdr files in the file open dialog.

Signed-off-by: John Arbuckle <programmingkidx@gmail.com>
Message-id: 32C964D4-3F17-47B7-AE7E-593E6BFD8855@gmail.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

ui/cocoa.m

@@ -874,7 +874,8 @@ - (id) init
 
         // set the supported image file types that can be opened
         supportedImageFileTypes = [NSArray arrayWithObjects: @"img", @"iso", @"dmg",
-                                 @"qcow", @"qcow2", @"cloop", @"vmdk", nil];
+                                 @"qcow", @"qcow2", @"cloop", @"vmdk", @"cdr",
+                                  nil];
     }
     return self;
 }