Re-conditionalize the correct portions.

Even though destination and broadcast address usually are the same
field, they have different names between Linux and BSD: ifa_ifu vs.
ifa_dstaddr.

Author: Markus Wanner (mwa)

src/ifaddrs.rs

@@ -45,12 +45,18 @@ impl InterfaceAddress {
             destination: None,
         };
 
-        let ifo = unsafe { SockAddr::from_libc_sockaddr(info.ifa_ifu) };
+        let ifu : *mut libc::sockaddr;
+
+        #[cfg(any(target_os = "linux", target_os = "emscripten", target_os = "fuchsia"))]
+        { ifu = info.ifa_ifu; }
+
+        #[cfg(not(any(target_os = "linux", target_os = "emscripten", target_os = "fuchsia")))]
+        { ifu = info.ifa_dstaddr; }
+
         if addr.flags.contains(IFF_POINTOPOINT) {
-            addr.destination = ifo;
-        }
-        if addr.flags.contains(IFF_BROADCAST) {
-            addr.broadcast = ifo;
+            addr.destination = unsafe { SockAddr::from_libc_sockaddr(ifu) };
+        } else if addr.flags.contains(IFF_BROADCAST) {
+            addr.broadcast = unsafe { SockAddr::from_libc_sockaddr(ifu) };
         }
 
         addr