... and move HAVE_FEATURE_EXTENSIONS there, too

Change-Id: I37fe52071e1db32cf5cc1e51dbd89bb4f32a39c1
Reviewed-on: https://gerrit.libreoffice.org/54072Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Rene Engelhard <rene@debian.org>