Fix stack overflow in OpenSolaris NEXTADDR()

Fix stack overflow in OpenSolaris NEXTADDR()

Commit 5fde831c5807 fixed NEXTADDR() for all *BSDs and MacOS.

OpenSolaris has to use a slightly different macro due to lack of
sockaddr->sa_len - but it has the same problem, first rounding up,
then memmove()'ing.  Switch order.

Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Arne Schwabe <arne@rfc2549.org>
Message-Id: <20200813101301.12720-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg20731.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 7e65483d1227adfb855844467e4d30894ffc355d)