macaddr: Use the BSD code for Darwin as well

It simply compiles, no other testing has been done.
diff --git a/src/macaddr.c b/src/macaddr.c
index 59c481f..a6e1304 100644
--- a/src/macaddr.c
+++ b/src/macaddr.c
@@ -47,7 +47,7 @@
 	return 0;
 }
 
-#if defined(__FreeBSD__)
+#if defined(__FreeBSD__) || defined(__APPLE__)
 #include <sys/socket.h>
 #include <sys/types.h>
 #include <ifaddrs.h>