RFR: 7900051 - jtreg cleanup intermittentely fails to delete files on Windows

[Jim Gish]

Please review: http://cr.openjdk.java.net/~jgish/Bug7900051-DeleteRetry/ 
<http://cr.openjdk.java.net/%7Ejgish/Bug7900051-DeleteRetry/>

Summary: this change adds delete retry logic on Windows similar to that 
that is already there on init.  It also consolidates the delete 
methods.  Instead of trying some N times with Delta msec. delay in 
between, it now tries for up to 30 seconds with Delta (500 msec) delay 
in between.

Thanks,
    Jim

-- 
Jim Gish | Consulting Member of Technical Staff | +1.781.442.0304
Oracle Java Platform Group | Core Libraries Team
35 Network Drive
Burlington, MA 01803
jim.gish at oracle.com