Add needed functions to glibc-compat for pkg

ports/glibc-compat/include/sys/un.h

Index: ports/glibc-compat/include/sys/un.h
diff --git a/ports/glibc-compat/include/sys/un.h b/ports/glibc-compat/include/sys/un.h
index 673c84b0bb6cfeb6dc9e4e92018861dd5d326819..2a9f994d694b52884e8e39f772b42fed4f726f24 100644
--- a/ports/glibc-compat/include/sys/un.h
+++ b/ports/glibc-compat/include/sys/un.h
@@ -1,4 +1,8 @@
-/* olonho */
+/*
+ * Copyright 2015 The Native Client Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
 #ifndef GLIBCEMU_SYS_UN_H
 #define GLIBCEMU_SYS_UN_H       1
 
@@ -9,6 +13,9 @@ struct sockaddr_un {
         char            sun_path[108];
 };
 
-#endif /* GLIBCEMU_SYS_UN_H */
-/* end of olonho */
+/* pulled from freebsd 10.1 sys/sys/un.h */
+/* actual length of an initialized sockaddr_un */
+#define SUN_LEN(su) \
+  (sizeof(*(su)) - sizeof((su)->sun_path) + strlen((su)->sun_path))
 
+#endif /* GLIBCEMU_SYS_UN_H */