RFR: 8057558 VirtualMachineImpl.execute on windows should close PipedInputStream before throwing exceptions

[Staffan Larsen]

Two fixes:
- The PipedInputStream used by the attach code on windows is not closed in case of errors
- The InputStreams returned by VirtualMachine.execute are not closed by all callers

webrev: http://cr.openjdk.java.net/~sla/8057558/webrev.00/
bug: https://bugs.openjdk.java.net/browse/JDK-8057558

Thanks,
/Staffan