Only define sa_family_t once.

Change-Id: Icf700910c836d22c8a27ad026ec8af11697edd5a
diff --git a/libc/include/bits/sa_family_t.h b/libc/include/bits/sa_family_t.h
new file mode 100644
index 0000000..51ea51f
--- /dev/null
+++ b/libc/include/bits/sa_family_t.h
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _BITS_SA_FAMILY_T_H_
+#define _BITS_SA_FAMILY_T_H_
+
+typedef unsigned short sa_family_t;
+
+#endif
diff --git a/libc/include/sys/socket.h b/libc/include/sys/socket.h
index 85999f3..9736ba8 100644
--- a/libc/include/sys/socket.h
+++ b/libc/include/sys/socket.h
@@ -40,10 +40,11 @@
 #include <linux/types.h>
 #include <linux/compiler.h>
 
+#include <bits/sa_family_t.h>
+
 __BEGIN_DECLS
 
 #define sockaddr_storage __kernel_sockaddr_storage
-typedef unsigned short sa_family_t;
 
 struct timespec;
 
diff --git a/libc/include/sys/un.h b/libc/include/sys/un.h
index 65ffbdcf..421b900 100644
--- a/libc/include/sys/un.h
+++ b/libc/include/sys/un.h
@@ -25,11 +25,11 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
+
 #ifndef _SYS_UN_H_
 #define _SYS_UN_H_
 
-typedef unsigned short sa_family_t;
-
+#include <bits/sa_family_t.h>
 #include <linux/un.h>
 
-#endif /* _SYS_UN_H_ */
+#endif