[8u] RFR for JDK-8162419: closed/com/oracle/jfr/runtime/TestVMInfoEvent.sh failing after JDK-8155968

[Shafi Ahmad]

Hi,

Please review the code change for "JDK-8162419: closed/com/oracle/jfr/runtime/TestVMInfoEvent.sh failing after JDK-8155968" to jdk8u.
Please note this is partial backport of http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/110ec5963eb1#l23.1

Summary:
Microsoft version of vsnprintf() behaves differently from the standard C version when there is not enough space in the buffer. 
Microsoft version doesn't null terminates its output under error conditions, whereas the standard C version does. On Windows, it returns -1. 
We handle both cases here and always return -1, and perform null termination.

Jdk8 bug: https://bugs.openjdk.java.net/browse/JDK-8162419
Webrev link: http://cr.openjdk.java.net/~shshahma/8162419/webrev.00/

Testing: jprt

Regards,
Shafi