Elon Musk has long wanted to call Warren Buffett a shareholder.Mike Blake/Reuters; Kevin Lamarque/ReutersElon Musk has long wished to have Warren Buffett as a shareholder.Buffett's Berkshire Hathaway now holds an indirect stake in Musk's SpaceX via Alphabet.Berkshire owned nearly 1% of Alphabet, which in turn owned about 4% of SpaceX, recent filings show.Elon Musk has wanted Warren Buffett as a shareholder for years. His wish has finally come tr…