Includes a revert of 58891d58 "Add distro-pack-
install-strip target to be used by dev-tools' flatpak/build.sh".

Change-Id: Ie2ba18bc13471b46e8d5f41868bae5aee17ff25f
Reviewed-on: https://gerrit.libreoffice.org/47599Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>