Makefile, tcp: Don't try to use tcpi_snd_wnd from tcp_info on pre-5.3 kernels

Detect missing tcpi_snd_wnd in struct tcp_info at build time,
otherwise build fails with a pre-5.3 linux/tcp.h header.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/tcp.h b/tcp.h
index bfd6082..dc854b8 100644
--- a/tcp.h
+++ b/tcp.h
@@ -67,7 +67,9 @@ struct tcp_ctx {
 	uint8_t port_to_init	[USHRT_MAX / 8];
 	int ns_detect_ports;
 	struct timespec timer_run;
+#ifdef HAS_SND_WND
 	int kernel_snd_wnd;
+#endif
 	size_t pipe_size;
 	struct timespec refill_ts;
 	struct timespec port_detect_ts;