Added all required dependencies

vendor/github.com/go-xorm/builder/cond_expr.go

@@ -0,0 +1,34 @@
+package builder
+
+import "fmt"
+
+type expr struct {
+	sql  string
+	args []interface{}
+}
+
+var _ Cond = expr{}
+
+func Expr(sql string, args ...interface{}) Cond {
+	return expr{sql, args}
+}
+
+func (expr expr) WriteTo(w Writer) error {
+	if _, err := fmt.Fprint(w, expr.sql); err != nil {
+		return err
+	}
+	w.Append(expr.args...)
+	return nil
+}
+
+func (expr expr) And(conds ...Cond) Cond {
+	return And(expr, And(conds...))
+}
+
+func (expr expr) Or(conds ...Cond) Cond {
+	return Or(expr, Or(conds...))
+}
+
+func (expr expr) IsValid() bool {
+	return len(expr.sql) > 0
+}