By Waakhe Simon Wudu JUBA (Reuters) -Up to 7.8 million people in South Sudan, two thirds of the population, may face severe food shortages during next year’s April-to-July lean season due to floods, drought and conflict, United Nations agencies said on Thursday. The shortages are worse than at the height of a civil war in 2013 and 2016, the Food and Agriculture Organization, the U.N. Children’s Fund UNICEF and the U.N. World Food Programme (WFP) said. “The decline in food security and high prevalence of malnutrition is linked to a combination of conflict, poor macroeconomic conditions, extreme…