By Bassam Masoud, Phil Stewart and James Mackenzie GAZA/MANAMA/JERUSALEM (Reuters) -Several countries have agreed to jointly carry out patrols in the southern Red Sea and Gulf of Aden to try to safeguard commercial shipping against attacks by Yemen’s Houthi rebels, who say they are supporting Palestinians under siege by Israel in the Gaza Strip. A statement on Tuesday by U.S. Defense Secretary Lloyd Austin, on a visit to Bahrain, identified several countries taking part in an international force. It was unclear whether those countries are willing to do what U.S. warships have done in recent da…