If a null-terminated string exactly of length MAX (0 byte included) is
provided, it will be handled as invalid because of wrong string size length
checks.
Commit fixes this.
Discovered during #1486 development.
This patch changes the top-level directory layout as a preparatory
step for improving the tools for managing 3rd-party source codes.
The rationale is described in the issue referenced below.
Issue #1082
Alexander Boettcher
Norman Feske