...so the $ are not eaten by the sub-make

Change-Id: Ifa9383a5d31720be517c03631224f5244f112d3d
Reviewed-on: https://gerrit.libreoffice.org/52775Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>