Update MentOs code to the latest development version.

programs/tests/t_sleep.c

@@ -0,0 +1,22 @@
+///                MentOS, The Mentoring Operating system project
+/// @file t_sleep.c
+/// @brief
+/// @copyright (c) 2014-2021 This file is distributed under the MIT License.
+/// See LICENSE.md for details.
+
+#include <sys/unistd.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/wait.h>
+#include <time.h>
+
+int main(int argc, char *argv[])
+{
+    printf("Sleeping for 4 seconds... ");
+    sleep(4);
+    printf("COMPLETED.\n");
+
+    return 0;
+}