Merge pull request #992 from SummerGGift/1013_patch_2

[lwIP] add lwip_tryget_socket API in lwIP 1.4.1.

components/net/lwip-1.4.1/src/api/sockets.c

@@ -231,6 +231,19 @@ tryget_socket(int s)
   return &sockets[s];
 }
 
+/**
+ * Same as tryget_socket but a global routine.
+ *
+ * @param s externally used socket index
+ * @return struct lwip_sock for the socket or NULL if not found
+ */
+struct lwip_sock *
+lwip_tryget_socket(int s)
+{
+	return tryget_socket(s);
+}
+
+
 /**
  * Allocate a new socket for a given netconn.
  *