RFR(s): 8072726: add adapter to convert Enumeration to Iterator

[Stuart Marks]

Hi all,

Please review this small API enhancement to add a default method "asIterator()" 
to Enumeration that converts it into an Iterator.

Webrev:

	http://cr.openjdk.java.net/~smarks/reviews/8072726/webrev.0/

Bug:

	https://bugs.openjdk.java.net/browse/JDK-8072726

Thanks,

s'marks