PipedWriter.java (flush): Throw exception if stream closed.

PipedWriter.java (flush): Throw exception if stream closed.

	* java/io/PipedWriter.java (flush): Throw exception if stream
	closed.
	* java/io/OutputStreamWriter.java (write): Throw exception if
	stream closed.
	(writeChars): Don't throw exception if stream closed.
	* java/io/CharArrayWriter.java (closed): New field.
	(close): Set it.
	(flush): Throw exception if stream closed.
	(reset): Synchronize on correct lock.  Allow stream to be
	reopened.
	(toCharArray, toString, writeTo): Synchronize.
	(write): Throwe exception if stream closed.
	* java/io/BufferedWriter.java (close): Clear `buffer'.
	(flush): Throw IOException if stream is closed.
	(write): Likewise.

From-SVN: r39927