databases/cego: update 2.51.5 -> 2.51.7

• Fix added in CegoFactor::getAggregationList: for case QUERY and case FETCH, the not-supported exceptions have been removed, otherwise this leads a useless exception in CegoAttrCond::asConjunctionList where aggregations are just checked
• Added grammer change in Cego.def to ensure operator precedence for AND and OR condition operator. AND has higher precedence if no enclosing braces are given. The result for the following queries should be the same select * from t1 where a = 42 or a = 1 and b = 'X' ; select * from t1 where a = 1 and b = 'X' or a = 42; select * from t1 where a = 42 or ( a = 1 and b = 'X' );
• With cego version before 2.51.7, braces have been mandatory to ensure operator precedence. With the new grammar extension, the AND operator has a higher presedence