all: fix Watch on Linux may fail on first read

Author: changkun

clipboard_linux.go

@@ -128,10 +128,7 @@ func write(t Format, buf []byte) (<-chan struct{}, error) {
 func watch(ctx context.Context, t Format) <-chan []byte {
 	recv := make(chan []byte, 1)
 	ti := time.NewTicker(time.Second)
-	last, err := read(t)
-	if err != nil {
-		return nil
-	}
+	last := Read(t)
 	go func() {
 		for {
 			select {