[4.1] 4da4d6b Make 4.1 compile on !linux again.

[Poul-Henning Kamp]

commit 4da4d6b3b7d5d2fbc66f4fbf7a10c6b062e0b8c6
Author: Poul-Henning Kamp <phk at FreeBSD.org>
Date:   Tue Jan 3 15:53:17 2017 +0000

    Make 4.1 compile on !linux again.
    
    Fixes: #2178

diff --git a/lib/libvarnish/vtcp.c b/lib/libvarnish/vtcp.c
index 62a9fb6..d28b99c 100644
--- a/lib/libvarnish/vtcp.c
+++ b/lib/libvarnish/vtcp.c
@@ -38,9 +38,7 @@
 #endif
 
 #include <netinet/in.h>
-#ifdef __linux
-#  include <netinet/tcp.h>
-#endif
+#include <netinet/tcp.h>
 
 #include <errno.h>
 #include <math.h>