$OpenBSD$

i think this helped build due to a missing define

--- src/sdl/i_system.cpp.orig	Fri Dec 28 21:11:28 2012
+++ src/sdl/i_system.cpp	Fri Dec 28 21:37:21 2012
@@ -41,6 +41,10 @@
 #include "doomerrors.h"
 #include <math.h>
 
+#ifdef __OpenBSD__
+#include <sys/wait.h>
+#endif
+
 #include "SDL.h"
 #include "doomtype.h"
 #include "doomstat.h"