don't send output of $$join() and $$sprintf() through split_value_list()

in the case of sprintf it's surprising, in the case of join it's
anti-thetical.

Change-Id: I4eb7e56d31ac6ed68adf852f1a19b33554d38eb4
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
(cherry picked from qtbase/ae94bf2b7a6373def9239ae5f54b143e1f6ffe09)