add vendor

vendor/qiniupkg.com/x/jsonutil.v7/unmarshal_string.go

@@ -0,0 +1,19 @@
+package jsonutil
+
+import (
+	"encoding/json"
+	"reflect"
+	"unsafe"
+)
+
+// ----------------------------------------------------------
+
+func Unmarshal(data string, v interface{}) error {
+
+	sh := *(*reflect.StringHeader)(unsafe.Pointer(&data))
+	arr := (*[1<<30]byte)(unsafe.Pointer(sh.Data))
+	return json.Unmarshal(arr[:sh.Len], v)
+}
+
+// ----------------------------------------------------------
+