Photo by DANIEL LEAL/AFP via Getty ImagesAFP via Getty ImagesShares in Diageo have extended their long-running slump on Thursday, after the Guinness maker cut guidance due to fresh sales troubles.Diageo’s share price was last trading 2.4% lower, at £17.53.At $4.9 billion, the FTSE 100 company’s net sales declined 2.2% in the three months to September. This chiefly reflected the negative impact of asset disposals, it said. Organic net sales flatlined in the first fiscal quarter, meanwhile. Though group volum ...