fdo#75757: remove inheritance to std::map

Change-Id: I189d7a1d68eb9022a32e882d68ce8c8dc567c1fd
Reviewed-on: https://gerrit.libreoffice.org/12042
Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>