Add HB_NO_OEPN (#1767)

diff --git a/src/hb-config.hh b/src/hb-config.hh
index bcce159..19ceed8 100644
--- a/src/hb-config.hh
+++ b/src/hb-config.hh
@@ -60,7 +60,9 @@
 #define HB_NO_GETENV
 #define HB_NO_LAYOUT_UNUSED
 #define HB_NO_MATH
+#define HB_NO_MMAP
 #define HB_NO_NAME
+#define HB_NO_OEPN
 #define HB_NO_SETLOCALE
 #define HB_NO_SUBSET_LAYOUT
 #endif