Note that, given that ws_rename() is a wrapper around ws_stdio_rename()

Note that, given that ws_rename() is a wrapper around ws_stdio_rename()
on Windows, and that ws_stdio_rename() uses MoveFileEx() with
MOVEFILE_REPLACE_EXISTING and should therefore remove the target if it
exists, the extra "remove the target first" stuff should not be
necessary on Windows - if we remove it, it also keeps the code from
removing the target and then having the rename fail, with the result
that the target no longer exists.

svn path=/trunk/; revision=42776