winexe: simulate epoll in case stdin does not support it

In Linux some file descriptors does not support
poll file operation (regular files for example).
Such fd should not be passed to tevent framework.
This patch adds code which deals with it for stdin.

Signed-off-by: Andrzej Hajda <andrzej.hajda@wp.pl>
winexe: add explicit int conversion to avoid warns

Signed-off-by: Andrzej Hajda <andrzej.hajda@wp.pl>