MILAN/PARIS (Reuters) - The board of French carmaker PSA (PEUP.PA), the owner of Peugeot, approved a binding agreement for a $50 billion merger with rival Fiat Chrysler (FCHA.MI), a source close to the matter said on Tuesday. A separate Fiat Chrysler (FCA) board meeting was under way to discuss finalizing the memorandum of understanding to create the world’s number four carmaker, the source added, in a deal that would reshape the global car industry. Both companies declined to comment.