* JavaScriptCore.vcproj/JavaScriptCore/copy-files.cmd: Don't try to delete directories that
don't exist. Also switched from del /s to rmdir /s, which has the benefit of deleting the
directory itself in addition to the files it contains.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@83299 268f45cc-cd09-0410-ab3c-d52691b4dbfc