ensure build_tcpinfo_message TCP_INFO check consistent with iperf_interval_results

Part of #935.

Change-Id: Id702dee9d894d91420719928ae2de6b44b72f579
Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
(cherry picked from commit 9dab732f5ec41be873cae3351b3d57fbfad36c93)
Signed-off-by: Bruce A. Mah <bmah@es.net>

src/tcp_info.c

@@ -197,13 +197,13 @@ get_pmtu(struct iperf_interval_results *irp)
 void
 build_tcpinfo_message(struct iperf_interval_results *r, char *message)
 {
-#if defined(linux)
+#if defined(linux) && defined(TCP_INFO)
     sprintf(message, report_tcpInfo, r->tcpInfo.tcpi_snd_cwnd, r->tcpInfo.tcpi_snd_ssthresh,
 	    r->tcpInfo.tcpi_rcv_ssthresh, r->tcpInfo.tcpi_unacked, r->tcpInfo.tcpi_sacked,
 	    r->tcpInfo.tcpi_lost, r->tcpInfo.tcpi_retrans, r->tcpInfo.tcpi_fackets, 
 	    r->tcpInfo.tcpi_rtt, r->tcpInfo.tcpi_reordering);
 #endif
-#if defined(__FreeBSD__)
+#if defined(__FreeBSD__) && defined(TCP_INFO)
     sprintf(message, report_tcpInfo, r->tcpInfo.tcpi_snd_cwnd,
 	    r->tcpInfo.tcpi_rcv_space, r->tcpInfo.tcpi_snd_ssthresh, r->tcpInfo.tcpi_rtt);
 #endif