types: Remove custom MacAddr type

The standard library has an ether_addr type that does the same job.

Change-Id: I98685b0b60dd07453ae2362adb33e0a7c9c3132c
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/test/test_neighbor.cpp b/test/test_neighbor.cpp
index a76a7d5..6491b9f 100644
--- a/test/test_neighbor.cpp
+++ b/test/test_neighbor.cpp
@@ -164,7 +164,7 @@
     EXPECT_EQ(ifstr, neighbors[0].interface);
     EXPECT_FALSE(neighbors[0].permanent);
     EXPECT_TRUE(neighbors[0].mac);
-    EXPECT_EQ(0, std::memcmp(&mac, neighbors[0].mac->data(), sizeof(mac)));
+    EXPECT_TRUE(equal(mac, *neighbors[0].mac));
     EXPECT_TRUE(equal(addr, std::get<in6_addr>(neighbors[0].address)));
 }