udplogserver: Flush output buffer when sent a message

* Because we are no longer adding a new line, which automatically
flushes the buffer.

tools/udplogserver/main.cpp

@@ -91,6 +91,7 @@ int main(int argc, char **argv)
          if (recvd > 0) {
             buffer[recvd] = 0;
             std::cout << buffer;
+            std::cout.flush();
          }
       }
    }