https://www.gnu.org/software/make/manual/html_node/Text-Functions.html

Change-Id: Ifb1d92cd9c7b59360d296026f01aa54ed83ed9c3
Reviewed-on: https://gerrit.libreoffice.org/52604Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>