$OpenBSD$

Need signal.h

Index: third_party/emu2/src/main.c
--- third_party/emu2/src/main.c.orig
+++ third_party/emu2/src/main.c
@@ -12,6 +12,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <math.h>
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
