w32: Remove cruft in w32-io from WindowsME times.

* src/w32-io.c (set_synchronize): Remove.
(create_reader, create_writer): No need for set_synchronize.

The set_synchronize dates back to 2001 at a time when I wrote the
Windows support on WindowsME and Windows2000. Maybe this was required
then due to bugs in that old NT or partly NT based Windows versions.

• Signed-off-by: Werner Koch <wk@gnupg.org>