move static constants out of ip6.h.

socket/socket_connected.c

@@ -0,0 +1,11 @@
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include "socket.h"
+
+int socket_connected(int s) {
+  struct sockaddr si;
+  socklen_t sl=sizeof si;
+  if (getpeername(s,&si,&sl))
+    return 0;
+  return 1;
+}