Fix build.
--- src/minizip/ioapi.h.ports.orig	Thu Aug  7 08:02:32 2014
+++ src/minizip/ioapi.h	Thu Aug  7 08:01:59 2014
@@ -50,7 +50,7 @@
 #define ftello64 ftell
 #define fseeko64 fseek
 #else
-#ifdef __FreeBSD__
+#if defined(__FreeBSD__) || defined(__OpenBSD__)
 #define fopen64 fopen
 #define ftello64 ftello
 #define fseeko64 fseeko