Restore interrupted flag in ImageIcon.loadImage

ImageIcon.loadImage used to handle InterruptedException only by printing a message to the console, JDK-8236987 handled the interrupted state more gracefully, but it didn't restore the interrupted flag.

Restoring the interrupted flag will allow the following code to handle interruption and exit the thread; otherwise, the thread will continue to run.

* “General-purpose task and library code should never swallow interruption requests.” — Java Concurrency in Practice, by Brian Goetz, Chapter 7. Cancellation and Shutdown, section 7.1.3 Responding to interruption.