$NetBSD$

Add NetBSD.
https://github.com/virtualsquare/vde-2/issues/70

--- CMakeLists.txt.orig	2026-08-03 10:48:09.000000000 +0000
+++ CMakeLists.txt
@@ -30,6 +30,8 @@ elseif(CMAKE_SYSTEM_NAME MATCHES "Darwin
     cm_define_var(VDE_DARWIN 1)
 elseif(CMAKE_SYSTEM_NAME MATCHES "FreeBSD")
     cm_define_var(VDE_FREEBSD 1)
+elseif(CMAKE_SYSTEM_NAME MATCHES "NetBSD")
+    cm_define_var(VDE_NETBSD 1)
 else()
     message(FATAL_ERROR "Unsupported OS: ${CMAKE_SYSTEM_NAME}")
 endif()
@@ -250,9 +252,9 @@ if(ENABLE_TUNTAP)
 	    set(ENABLE_TUNTAP OFF)
         endif()
 
-    elseif(CMAKE_SYSTEM_NAME MATCHES "FreeBSD")
+    elseif(CMAKE_SYSTEM_NAME MATCHES "FreeBSD|NetBSD")
         include(CheckIncludeFile)
-        cm_check_include("net/if_tun.h" HAVE_NET_IF_TUN_H)
+        cm_check_include("net/if.h;net/if_tun.h" HAVE_NET_IF_TUN_H)
         if(HAVE_NET_IF_TUN_H)
             add_definitions(-DHAVE_TUNTAP=1)
         else()
