VCS: fulltext indexing may not be done for some schemas

After the fix for NXP-4399 a bug is revealed : when a schema contains text fields and no list or complex fields, then fulltext reindexing is not triggered when a text field is updated.
NXP-4399 covered this up by needlessly updating list or complex fields of a schema on save() even when they hadn't changed.

dublincore and note schema all have complex or list fields so this didn't really appear in standard Nuxeo use.