-Wc23-extensions in net/ipv4/tcp_output.c

```
net/ipv4/tcp_output.c:663:2: error: label at end of compound statement is a C23 extension [-Werror,-Wc23-extensions]
  663 |         }
      |         ^
1 error generated.
```

This was a hard error in earlier releases:

```
net/ipv4/tcp_output.c:663:2: error: expected statement
        }
        ^
1 error generated.
```

I'll have a patch shortly.