RFR (S) 8152432: Implement setting jtreg @requires properties vm.flavor, vm.bits, vm.compMode

[Dmitry Fazunenko]

Hello,

Would you please review a relatively simple fix which starts using new 
jtreg functionality:
ability to define custom properties for use with the @requires tag.

https://bugs.openjdk.java.net/browse/JDK-8152432
http://cr.openjdk.java.net/~dfazunen/8152432/webrev.00/

As the first experience of using this functionality I just fixed setting 
of properties which set by jtreg,
but set incorrectly relying only on specified vm flags.
In the near future we are going to introduce new properties.

Tested locally.

Thanks,
Dima