Update MentOs code to the latest development version.

programs/tests/t_setenv.c

@@ -0,0 +1,29 @@
+///                MentOS, The Mentoring Operating system project
+/// @file t_setenv.c
+/// @brief
+/// @copyright (c) 2014-2021 This file is distributed under the MIT License.
+/// See LICENSE.md for details.
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/unistd.h>
+#include <sys/wait.h>
+
+int main(int argc, char *argv[])
+{
+    char *_argv[] = { "/bin/tests/t_getenv", NULL };
+    int status;
+
+    if (setenv("ENV_VAR", "pwd0", 0) == -1) {
+        printf("Failed to set env: `PWD`\n");
+        return 1;
+    }
+
+    if (fork() == 0) {
+        execv(_argv[0], _argv);
+        printf("This is bad, I should not be here! EXEC NOT WORKING\n");
+    }
+
+    wait(&status);
+    return 0;
+}