as recommended by W3C: https://www.w3.org/TR/xmldsig-core/#sec-PGPData

Reviewed-on: https://gerrit.libreoffice.org/40058Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>
(cherry picked from commit 9127706a)

Change-Id: I2cc0ae24eefc9137d2e3432da1d65e44245c7616
Reviewed-on: https://gerrit.libreoffice.org/40068Reviewed-by: Katarina Behrens <Katarina.Behrens@cib.de>
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>
Tested-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>