UPDATE 1-S.Africa's Naspers first-quarter results miss forecast(Adds details, quote)JOHANNESBURG, May 14 (Reuters) - South Africa’s Naspers, owner of 36 percent of China’s Tencent Holdings, reported a near-30 percent drop in first-quarter operating profit on Thursday, mainly due to lower earnings at its stake in the Asian internet company.Earnings before interest, tax, depreciation and amortisation (EBITDA) for the three months to end-March came in at 1.19 billion rand ($110 million), just below a 1.30 billion rand estimate by Thomson Reuters StarMine.“