GLOBAL MARKETS-Shares gain on strong U.S. GDP data, oil steadies

* U.S. Q3 GDP revised up to 5 pct annual pace * Dow, S&P 500 hit records, dollar gains * European shares gain on U.S., Spain, Portugal data * Brent crude oil steadies above $60 a barrel * Drop in Chinese shares drags (Updates to open of U.S. markets,...