Revert vendor directory to support old golang (GOPATH mode)

gomodule is still in progress to migrate for now, hence multus
team decide to keep vendor directory to support build without
gomodule.

vendor/github.com/json-iterator/go/reflect_dynamic.go

@@ -0,0 +1,70 @@
+package jsoniter
+
+import (
+	"github.com/modern-go/reflect2"
+	"reflect"
+	"unsafe"
+)
+
+type dynamicEncoder struct {
+	valType reflect2.Type
+}
+
+func (encoder *dynamicEncoder) Encode(ptr unsafe.Pointer, stream *Stream) {
+	obj := encoder.valType.UnsafeIndirect(ptr)
+	stream.WriteVal(obj)
+}
+
+func (encoder *dynamicEncoder) IsEmpty(ptr unsafe.Pointer) bool {
+	return encoder.valType.UnsafeIndirect(ptr) == nil
+}
+
+type efaceDecoder struct {
+}
+
+func (decoder *efaceDecoder) Decode(ptr unsafe.Pointer, iter *Iterator) {
+	pObj := (*interface{})(ptr)
+	obj := *pObj
+	if obj == nil {
+		*pObj = iter.Read()
+		return
+	}
+	typ := reflect2.TypeOf(obj)
+	if typ.Kind() != reflect.Ptr {
+		*pObj = iter.Read()
+		return
+	}
+	ptrType := typ.(*reflect2.UnsafePtrType)
+	ptrElemType := ptrType.Elem()
+	if iter.WhatIsNext() == NilValue {
+		if ptrElemType.Kind() != reflect.Ptr {
+			iter.skipFourBytes('n', 'u', 'l', 'l')
+			*pObj = nil
+			return
+		}
+	}
+	if reflect2.IsNil(obj) {
+		obj := ptrElemType.New()
+		iter.ReadVal(obj)
+		*pObj = obj
+		return
+	}
+	iter.ReadVal(obj)
+}
+
+type ifaceDecoder struct {
+	valType *reflect2.UnsafeIFaceType
+}
+
+func (decoder *ifaceDecoder) Decode(ptr unsafe.Pointer, iter *Iterator) {
+	if iter.ReadNil() {
+		decoder.valType.UnsafeSet(ptr, decoder.valType.UnsafeNew())
+		return
+	}
+	obj := decoder.valType.UnsafeIndirect(ptr)
+	if reflect2.IsNil(obj) {
+		iter.ReportError("decode non empty interface", "can not unmarshal into nil")
+		return
+	}
+	iter.ReadVal(obj)
+}