(Reuters) - London's FTSE 100 edged lower on Tuesday as Durex condom maker Reckitt Benckiser sank 5% and concerns that negotiations over the new Brexit deal could drag on weighed on domestic stocks.Reckitt fell to its lowest in more than one-and-a-half years after the company cut its sales view for the second time this year, leaving the blue-chip index 0.2% lower by 0740 GMT.However, losses were cushioned somewhat as Just Eat surged 21% to 717.4 pence after Dutch firm Prosus made a 710..