GRAINS-Corn eases as weather outlook, USDA data eyed
* Corn retreats after rallying on fears of hot, dry conditions * Some forecasts show wider rainfall, easing heat next week * Investors also adjust positions before USDA crop report * Wheat, soybeans fall (Updates with European trading, changes byline/dateline) By Gus Trompiz and Naveen Thukral PARIS/SINGAPORE, June 9 (Reuters) - Chicago corn fell on Wednesday as market