tcp: fastopen: note that a child socket was created

tcp: fastopen: note that a child socket was created

This uses up the last bit in a field of tcp_sock.

Signed-off-by: Jeremy Harris <jgh@exim.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Link: https://patch.msgid.link/20250423124334.4916-2-jgh@exim.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>