RFR: JDK-8014360-Optimize and Refactor the Normalize Process in java.io File Systems

[Dan Xu]

Hi,

The normalize() implementations in UnixFileSystem.java and 
WinNTFileSystem.java can be improved to make it simpler, easier, and 
more efficient. I have refactoredthecode when working on JDK-8003992. 
And Iwould like to send it out for a review in this separate bug. Thanks!

webrev: http://cr.openjdk.java.net/~dxu/8014360/webrev.00/

-Dan