fdo#60698: Unify spl and spl_unx

Change-Id: Ifd328ff3ce12364e95d05405759df6588b3a86bc
Reviewed-on: https://gerrit.libreoffice.org/6503
Tested-by: LibreOffice gerrit bot <gerrit@libreoffice.org>
Reviewed-by: Jan Holesovsky <kendy@collabora.com>
Tested-by: Jan Holesovsky <kendy@collabora.com>