fix count() …

COUNT（）函数逻辑有错误，本应该是在执行任何SQL的时候，都可以返回正确的行数。而现在复杂的SQL集合无法正确获取行数。

scope.go

@@ -950,7 +950,12 @@ func (scope *Scope) pluck(column string, value interface{}) *Scope {
 
 func (scope *Scope) count(value interface{}) *Scope {
 	if query, ok := scope.Search.selects["query"]; !ok || !countingQueryRegexp.MatchString(fmt.Sprint(query)) {
-		scope.Search.Select("count(*)")
+		if len(scope.Search.group) != 0 {
+			scope.Search.Select("count(*) FROM ( SELECT count(*) ")
+			scope.Search.group += " ) AS count"
+		} else {
+			scope.Search.Select("count(*)")
+		}
 	}
 	scope.Search.ignoreOrderQuery = true
 	scope.Err(scope.row().Scan(value))