Iraqis flocked to join anti-government protests after an influential cleric withdrew his support and security forces moved to quash the four-month-old uprising. A wave of students headed to protest sites in Baghdad and southern cities on Sunday, some of them chanting against populist cleric Moqtada al-Sadr, who on Friday said he would no longer be involved with the protests. Mr. Sadr sent thousands of his followers home, expressing disappointment with insults leveled against him by some anti-government protesters who…