MIDEAST STOCKS-Plunge on oil price drop, Fitch cut to Saudi outlook

* Indiscriminate selling across markets, sectors * Fitch feeds into concern about Saudi forwards move * Dubai falls 7 pct, biggest fall since December * Saudi Arabia's losses total 18 pct this month * Egypt caught up in emerging market scare By Andrew Torchia DUBAI, Aug 23 (Reuters) - Major Middle Eastern stock markets plunged in relentless selling on Sunday because of sliding oil prices, a decision by Fitch Ratings to cut its outlook for Saudi Arabia's debt, and Friday'