RFR 8051953: Add Unreachable.java test to ProblemList on Windows

[Wang Weijun]

Please review the code change at

   http://cr.openjdk.java.net/~weijun/8051953/webrev.00/test/ProblemList.txt.udiff.html

which add one item into test/ProblemList.txt

+# 8051952: Unreachable.java test failing on Windows
+sun/security/krb5/auto/Unreachable.java                         windows-all

The test started failing since July 13 on multiple test machines. The reason is that a UDP receive() call does not throw an UnreachablePortException. Microsoft's own portqry.exe also cannot receive the ICMP destination unreachable message.

This might be due to a change of network configuration.

Thanks
Max