set POSIX_FADV_SEQUENTIAL if not present

File.cpp

@@ -13,6 +13,10 @@
 #include "xml/File.h"
 #include "xml/NamedEnts.h"
 
+#ifndef POSIX_FADV_SEQUENTIAL
+#define POSIX_FADV_SEQUENTIAL 2
+#endif
+
 using namespace xml;
 
 // _____________________________________________________________________________