Move openvpn_sleep() to manage.c

Move openvpn_sleep() to manage.c

openvpn_sleep() is basically "service the management interface for x
seconds, then return".  Therefore, manage.c is a more suitable location
than the random collection of unrelated stuff called misc.c.

(I think we should find a better place for everything currently in misc.c,
and get rid of it all together.  This patch is part of that effort.)

Signed-off-by: Steffan Karger <steffan.karger@fox-it.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1500566435-29920-1-git-send-email-steffan.karger@fox-it.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg15109.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>