pool: remove useless 'options.h' include

pool: remove useless 'options.h' include

Commit 6a8cd033 ("pool: add support for ifconfig-pool-persist with IPv6
only") has accidentally introduced an include for 'options.h', which
revealed to not be useful at all. Remove it.

Reported-by: Gert Doering <gert@greenie.muc.de>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20200610090100.29738-1-a@unstable.cc>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg20011.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>