(Corrects date of story to Jan 18 from Jan 17) DUBLIN (Reuters) -Online betting giant Flutter posted a 15% rise in fourth-quarter revenue on Thursday but said growth of 26% in its Fanduel U.S. business was below expectations due to a series of very friendly customer results. The world’s largest online betting company said in November that it expected full-year earnings excluding the nascent U.S. market of 1.44 billion pounds, the bottom of its previously forecast range following a similar run of results in Europe. It is due to report earnings figures on March 26 but in a post-close statement o…