RFR: 8022213 Intermittent test failures in java/net/URLClassLoader (Add jdk/testlibrary/FileUtils.java)

[Chris Hegarty]

Virus checkers and, on more modern Windows OSes, Windows Experience 
Service, and other external processes, have been causing trouble when it 
comes to tests deleting files.

On a number of occasions in the past retry logic has been added to tests 
that need to delete files. Also, the jtreg harness has similar logic 
when cleaning up temporary files.

This has reared its head again with:
   8027902: TEST_BUG: java/net/URLClassLoader/closetest/CloseTest.java 
and java/net/URLClassLoader/closetest/GetResourceAsStream.java failed 
due to dir operation failed.
   8022213: Intermittent test failures in java/net/URLClassLoader

I'd like to add file utility functions to the common jdk/testlibrary, 
starting with a "more reliable" delete. I've made minimal changes to the 
URLClassloader tests to use this ( more could be done, but this is just 
a start ).

http://cr.openjdk.java.net/~chegar/fileUtils/webrev/

The important part here for review is the "API" and impl in FileUtils.

Thanks,
-Chris.