trail_ref cleanup

git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@64 b08c6af1-5177-4d33-ba66-4b1c6b8b522a

library/system/sys.c

@@ -672,6 +672,16 @@ pid(void)
 #endif
 }
 
+static int
+win(void)
+{
+#if defined(__MINGW32__) || _MSC_VER
+  return(TRUE);
+#else
+  return(FALSE);
+#endif
+}
+
 static int
 p_kill(void)
 {
@@ -732,6 +742,7 @@ init_sys(void)
   UserCPredicate("rename_file", rename_file, 3);
   UserCPredicate("sleep", p_sleep, 2);
   UserCPredicate("error_message", error_message, 2);
+  UserCPredicate("win", win, 0);
 }
 
 #ifdef _WIN32