HAVANA, Sept 15 (Reuters) - United Nations Secretary-General Antonio Guterres on Friday praised efforts to support the Global South in the international arena as he opened a summit of the G77 group of developing nations and China with host Cuba. The focus is the scientific and technological divide between rich and poor countries and its impact on development. Guterres said greater international equality was essential to building the consensus needed to tackle climate change and inequality. "The world is failing developing nations" he said, expressing the hope that the meeting would strengthen participants' clout on a wide range of issues....