$OpenBSD: patch-tools_gn_args_cc,v 1.1 2016/10/27 18:30:41 robert Exp $
--- tools/gn/args.cc.orig.port	Wed Oct 19 13:53:46 2016
+++ tools/gn/args.cc	Wed Oct 19 13:54:01 2016
@@ -260,6 +260,8 @@ void Args::SetSystemVarsLocked(Scope* dest) const {
   os = "android";
 #elif defined(OS_NETBSD)
   os = "netbsd";
+#elif defined(OS_OPENBSD)
+  os = "openbsd";
 #else
   #error Unknown OS type.
 #endif
