Socket interface: Added close() interface.

net/socket/socket.h

@@ -506,6 +506,24 @@ ssize_t inet_recvfrom(FAR struct socket *psock, FAR void *buf, size_t len,
                       int flags, FAR struct sockaddr *from,
                       FAR socklen_t *fromlen);
 
+/****************************************************************************
+ * Name: inet_close
+ *
+ * Description:
+ *   Performs the close operation on an AF_INET or AF_INET6 socket instance
+ *
+ * Parameters:
+ *   psock   Socket instance
+ *
+ * Returned Value:
+ *   0 on success; -1 on error with errno set appropriately.
+ *
+ * Assumptions:
+ *
+ ****************************************************************************/
+
+int inet_close(FAR struct socket *psock);
+
 #undef EXTERN
 #if defined(__cplusplus)
 }