RFR(xs): 8149184: os::is_server_class_machine() could return incorrect result if a host's cpu have a few logical cores

[Kirill Zhaldybin]

Dear all,

Could you please review a small fix for JDK-8149184?

It fixes server class machine discovery in case if a host has 2 physical 
cpu with 2 threads for core each.

CR: https://bugs.openjdk.java.net/browse/JDK-8149184

WebRev: http://cr.openjdk.java.net/~kzhaldyb/webrevs/JDK-8149184/webrev.00/

Thank you.

Regards, Kirill