MIDEAST STOCKS-Gulf up on stronger global trend, long-term outlook still murky

* Markets appear to have established short-term floors * Saudi petrochemical shares surge on stronger oil * But long-term uncertainty over oil, economic policy remains * Trading turnover shrinks; FX forwards, CDS still high * Egypt's Pioneers Holding leaps after Q2 earnings By Andrew Torchia DUBAI, Aug 27 (Reuters) - Major Gulf stock markets rose sharply on Thursday, suggesting they had established short-term floors after several weeks of heavy selling, but their long-te