Warren Buffett has given up his long-held conviction against buying gold — and he’s meanwhile getting out of Goldman Sachs. The totemic tycoon revealed in filings late last week that he has scooped up more than 20 million shares of mining giant Barrick Gold Corp. even as he unloaded nearly all of his nearly 2 million shares in Goldman Sachs. The 89-year-old investing icon’s sudden embrace of the precious yellow metal — which has has previously derided as “useless,” saying that “anyone watching from Mars would be scratching their head” at the idea of investing in it — took many...