Implement workaround of socketpair()

    new file:   io/socketpair.c

io/socketpair.c

@@ -0,0 +1,27 @@
+/*
+ * socketpair() workaround for OS/2 kLIBC
+ *
+ * Copyright (C) 2024 KO Myung-Hun <[email protected]>
+ *
+ * This program is free software. It comes without any warranty, to
+ * the extent permitted by applicable law. You can redistribute it
+ * and/or modify it under the terms of the Do What The Fuck You Want
+ * To Public License, Version 2, as published by Sam Hocevar. See
+ * http://www.wtfpl.net/ for more details.
+ */
+
+/*
+ * Dependencies: None
+ */
+
+#include <stdio.h>
+
+/* OS/2 kLIBC quits a program without flushing a stream associated with a
+ * socket. This leads to loss of buffered data of a stream. So flush before
+ * a program ends.
+ */
+__attribute__((destructor))
+static void flush( void )
+{
+    flushall();
+}