By John McCrank, Michelle Price and Iain Withers (Reuters) -British lender Barclays agreed a $361 million penalty with U.S. regulators on Thursday for “staggering” failures that led it to oversell $17.7 billion of structured products, racking up further costs for an error that has blighted CEO C.S. Venkatakrishnan’s first year in charge. The bank said after London market close on Friday that its own review led by external lawyers into the error had also concluded, adding it would consider individual accountabilities and whether to take disciplinary action or dock pay packets based on the findi…