Fix termination when windows suspends/sleeps

Fix termination when windows suspends/sleeps

When TUN/TAP I/O operation is aborted, restart with a SIGHUP instead of
terminate. The abort error from TAP is often triggered by system suspend
which is fully recoverable on resume. Catastrophic events will get caught
later during the restart.  This solves the abnormal termination during
suspend/resume.

Signed-off-by: Selva Nair <selva.nair@gmail.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1446663578-14471-1-git-send-email-selva.nair@gmail.com>
URL: http://article.gmane.org/gmane.network.openvpn.devel/10438
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit ea66a2b5cdb21422139c421b4d3733e1c1c3937e)