rtnetlink: Return neighbor even if addr is missing

There are valid configurations that return these type of messages from
the kernel and we don't want to fail for them

Change-Id: I74a0fd519e553c2e4bc3e114e7563fe93d8facf6
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/test/test_rtnetlink.cpp b/test/test_rtnetlink.cpp
index 8bf2a1e..7b60072 100644
--- a/test/test_rtnetlink.cpp
+++ b/test/test_rtnetlink.cpp
@@ -69,8 +69,8 @@
     {
         alignas(NLMSG_ALIGNTO) ndmsg ndm = {};
     } msg;
-    EXPECT_THROW(neighFromRtm(stdplus::raw::asView<char>(msg)),
-                 std::runtime_error);
+
+    EXPECT_EQ((NeighborInfo{}), neighFromRtm(stdplus::raw::asView<char>(msg)));
 }
 
 TEST(NeighFromRtm, NoMac)