RFR(M) : 8182154 : merge jdk.testlibrary.Platform and jdk.test.lib.Platform

[Igor Ignatyev]

http://cr.openjdk.java.net/~iignatyev/8182154/webrev.01/
> 281 lines changed: 18 ins; 223 del; 40 mod;

Hi all,

could you please review this changeset which removes Platform from jdk testlibrary and updates tests to use jdk.test.lib.Platform from top level testlibrary instead?
as a part of this patch, I've also cleaned up jdk.test.lib.Platform a bit.

testing: all changed tests locally, jdk/test/:tier[1-3]
webrev: http://cr.openjdk.java.net/~iignatyev/8182154/webrev.01/
jbs: https://bugs.openjdk.java.net/browse/JDK-8182154

Thanks,
-- Igor