RFR(S) : 8178415: remove ProcessTools::getPlatformSpecificVMArgs from testlibary

[Igor Ignatyev]

http://cr.openjdk.java.net/~iignatyev/8178415/webrev.00/
> 59 lines changed: 0 ins; 59 del; 0 mod;

Hi all,

could you please review this small clean up of testlibaries?
the only platform specific vm arguments which we had were -d64/32. they were deprecated in jdk9 by 8168010 and will be removed in jdk10 by 8169646. therefore ProcessTools::getPlatformSpecificVMArgs method is not needed anymore and should be removed.

JBS: https://bugs.openjdk.java.net/browse/JDK-8178415
webrev: http://cr.openjdk.java.net/~iignatyev/8178415/webrev.00/
testing: :jdk_tier{1-3}, :hotspot_all
8168010: https://bugs.openjdk.java.net/browse/JDK-8168010
8169646: https://bugs.openjdk.java.net/browse/JDK-8169646

Thanks,
-- Igor