RFR(XS): 8180802 : move jdk.testlibrary.management.ThreadMXBeanTool to top level testlibrary

[Igor Ignatyev]

http://cr.openjdk.java.net/~iignatyev//8180802/webrev.00/index.html
> 143 lines changed: 71 ins; 72 del; 0 mod; 
Hi all,

could you please review this patch which moves ThreadMXBeanTool from jdk testlibrary to the top level testlibrary?
please be aware that there are tests outside jdk repository which use this class. these tests will be updated accordingly.

webrev: http://cr.openjdk.java.net/~iignatyev//8180802/webrev.00/index.html
jbs: https://bugs.openjdk.java.net/browse/JDK-8180802

Thanks,
-- Igor