RFR: JDK-8013827 and JDK-8011950, , java.io.File.createTempFile enters infinite loop when passed invalid data

[Dan Xu]

Hi All,

When File.createTempFile() is called with some special parameters, it 
runs into infiniteloop and hangs. It is because it does not always mean 
a file exists when the method, createFileExclusively(), returns false. 
This fix is going to solve such issues reported in JDK-8013827 and 
JDK-8011950.And I also added some testcases to verify it.

webrev: http://cr.openjdk.java.net/~dxu/8013827/webrev.00/
bug: http://bugs.sun.com/view_bug.do?bug_id=8011950

-Dan