RFR: [test,16] JDK-8164597 : TestIOException.java fails after push for JDK-8164130.

[Jonathan Gibbons]

Please review a change to enable a javadoc test to be removed from the 
problem list.

The test was excluded because an IOException was occurring when running 
the test
on Windows, Most of the change here is support code to diagnose the 
problem, and
to investigate whether the issue can be fixed.

Eventually, a reference was found on a Microsoft site, indicating that 
normal directories
cannot be made read-only on Windows.  Thus the primary fix is to skip 
each test-case
if the setup for the test case fails to create a readonly directory on 
Windows.

In addition doc comments and -Xdoclint:-missing are added to reduce the 
number of
irrelevant diagnostics in the output.

In conjunction with the fix for JDK-8152313, this will fix all javadoc 
tests on the
LangTools exclude list.

-- Jon

JBS: https://bugs.openjdk.java.net/browse/JDK-8164597
Webrev: http://cr.openjdk.java.net/~jjg/8164597/webrev.00/