route.c: pass the right parameter to IN6_IS_ADDR_UNSPECIFIED

route.c: pass the right parameter to IN6_IS_ADDR_UNSPECIFIED

IN6_IS_ADDR_UNSPECIFIED on most systems is defined as a macro that
expects a struct in6_addr* argument.

In one instance we are passing the right address but using a wrong type.
Fix this invocation by properly passing the right pointer.

This issue might become more critical on systems implementing
IN6_IS_ADDR_UNSPECIFIED as a function rather than a macro.

Signed-off-by: Antonio Quartulli <a@unstable.cc>
Acked-by:
Message-Id: <20210826061725.22169-1-a@unstable.cc>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg22767.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit aa0e44e235f7bee0e12707b6899d00bad85195fc)