OpenBSD doesn't support timeb api
add SI_ASYNCIO define

--- src/c/wrapper_unix.c.orig	Fri Jul 31 18:22:16 2020
+++ src/c/wrapper_unix.c	Fri Jul 31 18:23:10 2020
@@ -51,7 +51,6 @@
 #include <pthread.h>
 #include <pwd.h>
 #include <sys/resource.h>
-#include <sys/timeb.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/wait.h>
@@ -466,8 +465,10 @@ const TCHAR* getSignalCodeDesc(int code) {
         return TEXT("mesq state changed");
 #endif
 
+#ifdef SI_ASYNCIO
     case SI_ASYNCIO:
         return TEXT("AIO completed");
+#endif
 
 #ifdef SI_SIGIO
     case SI_SIGIO: