vendor the latest json-iterator

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

@@ -2,9 +2,10 @@ package jsoniter
 
 import (
 	"fmt"
-	"github.com/modern-go/reflect2"
 	"reflect"
 	"unsafe"
+
+	"github.com/modern-go/reflect2"
 )
 
 // ValDecoder is an internal type registered to cache as needed.
@@ -40,6 +41,14 @@ type ctx struct {
 	decoders map[reflect2.Type]ValDecoder
 }
 
+func (b *ctx) caseSensitive() bool {
+	if b.frozenConfig == nil {
+		// default is case-insensitive
+		return false
+	}
+	return b.frozenConfig.caseSensitive
+}
+
 func (b *ctx) append(prefix string) *ctx {
 	return &ctx{
 		frozenConfig: b.frozenConfig,