Update MentOs code to the latest development version.

libc/src/sys/unistd.c

@@ -0,0 +1,37 @@
+///                MentOS, The Mentoring Operating system project
+/// @file unistd.c
+/// @brief Functions used to manage files.
+/// @copyright (c) 2014-2021 This file is distributed under the MIT License.
+/// See LICENSE.md for details.
+
+#include "sys/unistd.h"
+#include "string.h"
+#include "limits.h"
+#include "stdio.h"
+
+#if 0
+#include "vfs.h"
+
+int rmdir(const char *path)
+{
+    char absolute_path[PATH_MAX];
+
+    get_absolute_normalized_path(path, absolute_path);
+
+    int32_t mp_id = get_mountpoint_id(absolute_path);
+    if (mp_id < 0) {
+        printf("rmdir: failed to remove '%s':"
+               "Cannot find mount-point\n",
+               path);
+
+        return -1;
+    }
+
+    if (mountpoint_list[mp_id].dir_op.rmdir_f == NULL) {
+        return -1;
+    }
+
+    return mountpoint_list[mp_id].dir_op.rmdir_f(absolute_path);
+}
+
+#endif