configure: we need both cups header and library

Change-Id: Ie27a67b7d1086fbbce5eb40a56b4d154afb3faf8
(cherry picked from commit 3b3c8c4796a89a76ce7574908096a91993412523)
Reviewed-on: https://gerrit.libreoffice.org/7348
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>