trivial: Use correct test in configure check for gcab
trivial: Use correct test in configure check for gcab

hughsie/fwupd,superm1/fwupd,vathpela/fwupd,vathpela/fwupd,fwupd/fwupd,vathpela/fwupd,vathpela/fwupd,hughsie/fwupd,fwupd/fwupd,fwupd/fwupd,superm1/fwupd,hughsie/fwupd,hughsie/fwupd,superm1/fwupd,fwupd/fwupd