Fix build with recent fribidi

Index: src/unicode.c
--- src/unicode.c.orig
+++ src/unicode.c
@@ -25,10 +25,10 @@
  *  defines the routines used to manipulate Unicode strings and characters
  */
 
-#include <fribidi/fribidi.h>
-
 #include "internal.h"
 
+#undef HAVE_CONFIG_H
+#include <fribidi/fribidi.h>
 
 
 /* Find a Unicode name from its code */