GLOBAL MARKETS-China gains, auto sector lift Asian shares, but sentiment fragile

* MSCI Asia ex-Japan +0.38%; Nikkei +0.37%* European markets seen opening higher* Analysts see widespread uncertainty, continued risk aversion* Brent crude wavers around $70 per barrel* Asian stock markets: https://tmsnrt.rs/2zpUAr4By Andrew GalbraithSHANGHAI, May 28 (Reuters) - Asian shares rose on Tuesday, lifted by gains in China and as auto firms climbed on merger news, but broad uncertainties