virSocketAddrIsWildcard: Use IN6_IS_ADDR_UNSPECIFIED correctly
virSocketAddrIsWildcard: Use IN6_IS_ADDR_UNSPECIFIED correctly

https://bugzilla.redhat.com/show_bug.cgi?id=920441

The IN6_IS_ADDR_UNSPECIFIED macro expects pointer to sin6_addr element
instead of s6_addr element.
(cherry picked from commit 7793d2a83e437fb5ebc7a35dd37455aa74a547b2)

mithleshvrts/libvirt-0.10.2,mithleshvrts/libvirt-0.10.2,mithleshvrts/libvirt-0.10.2,mithleshvrts/libvirt-0.10.2,mithleshvrts/libvirt-0.10.2