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_slice.go

@@ -0,0 +1,99 @@
+package jsoniter
+
+import (
+	"fmt"
+	"github.com/modern-go/reflect2"
+	"io"
+	"unsafe"
+)
+
+func decoderOfSlice(ctx *ctx, typ reflect2.Type) ValDecoder {
+	sliceType := typ.(*reflect2.UnsafeSliceType)
+	decoder := decoderOfType(ctx.append("[sliceElem]"), sliceType.Elem())
+	return &sliceDecoder{sliceType, decoder}
+}
+
+func encoderOfSlice(ctx *ctx, typ reflect2.Type) ValEncoder {
+	sliceType := typ.(*reflect2.UnsafeSliceType)
+	encoder := encoderOfType(ctx.append("[sliceElem]"), sliceType.Elem())
+	return &sliceEncoder{sliceType, encoder}
+}
+
+type sliceEncoder struct {
+	sliceType   *reflect2.UnsafeSliceType
+	elemEncoder ValEncoder
+}
+
+func (encoder *sliceEncoder) Encode(ptr unsafe.Pointer, stream *Stream) {
+	if encoder.sliceType.UnsafeIsNil(ptr) {
+		stream.WriteNil()
+		return
+	}
+	length := encoder.sliceType.UnsafeLengthOf(ptr)
+	if length == 0 {
+		stream.WriteEmptyArray()
+		return
+	}
+	stream.WriteArrayStart()
+	encoder.elemEncoder.Encode(encoder.sliceType.UnsafeGetIndex(ptr, 0), stream)
+	for i := 1; i < length; i++ {
+		stream.WriteMore()
+		elemPtr := encoder.sliceType.UnsafeGetIndex(ptr, i)
+		encoder.elemEncoder.Encode(elemPtr, stream)
+	}
+	stream.WriteArrayEnd()
+	if stream.Error != nil && stream.Error != io.EOF {
+		stream.Error = fmt.Errorf("%v: %s", encoder.sliceType, stream.Error.Error())
+	}
+}
+
+func (encoder *sliceEncoder) IsEmpty(ptr unsafe.Pointer) bool {
+	return encoder.sliceType.UnsafeLengthOf(ptr) == 0
+}
+
+type sliceDecoder struct {
+	sliceType   *reflect2.UnsafeSliceType
+	elemDecoder ValDecoder
+}
+
+func (decoder *sliceDecoder) Decode(ptr unsafe.Pointer, iter *Iterator) {
+	decoder.doDecode(ptr, iter)
+	if iter.Error != nil && iter.Error != io.EOF {
+		iter.Error = fmt.Errorf("%v: %s", decoder.sliceType, iter.Error.Error())
+	}
+}
+
+func (decoder *sliceDecoder) doDecode(ptr unsafe.Pointer, iter *Iterator) {
+	c := iter.nextToken()
+	sliceType := decoder.sliceType
+	if c == 'n' {
+		iter.skipThreeBytes('u', 'l', 'l')
+		sliceType.UnsafeSetNil(ptr)
+		return
+	}
+	if c != '[' {
+		iter.ReportError("decode slice", "expect [ or n, but found "+string([]byte{c}))
+		return
+	}
+	c = iter.nextToken()
+	if c == ']' {
+		sliceType.UnsafeSet(ptr, sliceType.UnsafeMakeSlice(0, 0))
+		return
+	}
+	iter.unreadByte()
+	sliceType.UnsafeGrow(ptr, 1)
+	elemPtr := sliceType.UnsafeGetIndex(ptr, 0)
+	decoder.elemDecoder.Decode(elemPtr, iter)
+	length := 1
+	for c = iter.nextToken(); c == ','; c = iter.nextToken() {
+		idx := length
+		length += 1
+		sliceType.UnsafeGrow(ptr, length)
+		elemPtr = sliceType.UnsafeGetIndex(ptr, idx)
+		decoder.elemDecoder.Decode(elemPtr, iter)
+	}
+	if c != ']' {
+		iter.ReportError("decode slice", "expect ], but found "+string([]byte{c}))
+		return
+	}
+}