By Farah Saafan CAIRO (Reuters) -Egyptians headed to the polls on Sunday for a presidential election in which Abdel Fattah al-Sisi is poised to win a third term in power as the country grapples with an economic crisis and a war on its border with Gaza. Victory would hand Sisi a six-year term in which immediate priorities would be taming near-record inflation, managing a chronic foreign currency shortage and preventing spillover from the conflict between Israel and Gaza’s Hamas rulers. Voting, which runs from 9 a.m. until 9 p.m. (0700-1900 GMT), is spread over three days, with results due to be…