Added all required dependencies

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

@@ -0,0 +1,74 @@
+package builder
+
+import (
+	"bytes"
+	"io"
+)
+
+type Writer interface {
+	io.Writer
+	Append(...interface{})
+}
+
+type stringWriter struct {
+	writer *bytes.Buffer
+	buffer []byte
+	args   []interface{}
+}
+
+func NewWriter() *stringWriter {
+	w := &stringWriter{}
+	w.writer = bytes.NewBuffer(w.buffer)
+	return w
+}
+
+func (s *stringWriter) Write(buf []byte) (int, error) {
+	return s.writer.Write(buf)
+}
+
+func (s *stringWriter) Append(args ...interface{}) {
+	s.args = append(s.args, args...)
+}
+
+type Cond interface {
+	WriteTo(Writer) error
+	And(...Cond) Cond
+	Or(...Cond) Cond
+	IsValid() bool
+}
+
+type condEmpty struct{}
+
+var _ Cond = condEmpty{}
+
+func NewCond() Cond {
+	return condEmpty{}
+}
+
+func (condEmpty) WriteTo(w Writer) error {
+	return nil
+}
+
+func (condEmpty) And(conds ...Cond) Cond {
+	return And(conds...)
+}
+
+func (condEmpty) Or(conds ...Cond) Cond {
+	return Or(conds...)
+}
+
+func (condEmpty) IsValid() bool {
+	return false
+}
+
+func condToSQL(cond Cond) (string, []interface{}, error) {
+	if cond == nil || !cond.IsValid() {
+		return "", nil, nil
+	}
+
+	w := NewWriter()
+	if err := cond.WriteTo(w); err != nil {
+		return "", nil, err
+	}
+	return w.writer.String(), w.args, nil
+}