psock_send() no longer sets errno, so send() must now set it.

net/socket/send.c

@@ -224,6 +224,12 @@ ssize_t send(int sockfd, FAR const void *buf, size_t len, int flags)
   /* And let psock_send do all of the work */
 
   ret = psock_send(psock, buf, len, flags);
+  if (ret < 0)
+    {
+      set_errno((int)-ret);
+      ret = ERROR;
+    }
+
   leave_cancellation_point();
   return ret;
 }