Please consider this patches for 4.0.1
1/ Allow to use system tcpdf (as for gettext)
https://github.com/remicollet/phpmyadmin/commit/4eb620b13b29c566f868800b6ae…
2/ Compatibility with tcpdf 6.0
https://github.com/remicollet/phpmyadmin/commit/6d181676fab4c531f499cdafdc8…
Regards,
Remi.
P.S. Sorry, I will not send any more PR, github is just a nightmare for
an occasional contributor.