--with-referenced-git works with submodules, --with-linked-git does not.
And I don't see a way to fix it, either.

Change-Id: Ib6cdb065a022665cd62e9fdc7fc37a9e916e50ad
Reviewed-on: https://gerrit.libreoffice.org/2165Reviewed-by: Matúš Kukan <matus.kukan@gmail.com>
Reviewed-by: Björn Michaelsen <bjoern.michaelsen@canonical.com>
Reviewed-by: Miklos Vajna <vmiklos@suse.cz>
Tested-by: Miklos Vajna <vmiklos@suse.cz>