Fix launching of dbus-daemon on Windows in paths containing spaces

Fix launching of dbus-daemon on Windows in paths containing spaces

If dbus is installed in a path, which contains a space, dbus-launch will
not launch the daemon. That is so, because a command line is built from
just the path to the daemon and a parameter. The path has to be
surrounded with quotes. This can be done unconditionally, because the
quotes do not cause any trouble even if they are not needed.

Reviewed-by: Ralf Habacker <ralf.habacker@freenet.de>
Bug: https://bugs.freedesktop.org/show_bug.cgi?id=49450