RFR: 8028354 jstat does not provide enough information when fail to read data from remote JVM

[Staffan Larsen]

Please review the following small change to provide more information from jstat 
when it fails.

bug: https://bugs.openjdk.java.net/browse/JDK-8028354
webrev: http://cr.openjdk.java.net/~sla/8028354/webrev.00/

Thanks,
/Staffan