RFR: JDK-8023430 - Replace File.mkdirs with Files.createDirectories to get MaxPathLength.java failure details

[Dan Xu]

Hi,

MaxPathLength.java testcase failed intermittently. And File.mkdirs() 
does not throw any exceptions when it fails, which makes it even harder 
for the diagnosis. As Alan suggested, I'd like to change it to 
Files.createDirectories to get detailed exceptions once a failure 
happens. Thanks!

webrev: http://cr.openjdk.java.net/~dxu/8023430/webrev/
bug: http://bugs.sun.com/view_bug.do?bug_id=8023430

-Dan