Add missing vendor into vendor.conf.

Signed-off-by: Lantao Liu <lantaol@google.com>

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

@@ -25,7 +25,7 @@ func (iter *Iterator) ReadBool() (ret bool) {
 		iter.skipFourBytes('a', 'l', 's', 'e')
 		return false
 	}
-	iter.ReportError("ReadBool", "expect t or f")
+	iter.ReportError("ReadBool", "expect t or f, but found "+string([]byte{c}))
 	return
 }
 
@@ -59,7 +59,9 @@ func (iter *Iterator) stopCapture() []byte {
 	iter.captureStartedAt = -1
 	iter.captured = nil
 	if len(captured) == 0 {
-		return remaining
+		copied := make([]byte, len(remaining))
+		copy(copied, remaining)
+		return copied
 	}
 	captured = append(captured, remaining...)
 	return captured