RFR(S) : 8172149 : CTW library should call System::exit

[Igor Ignatyev]

http://cr.openjdk.java.net/~iignatyev/8172149/webrev.00/
> 61 lines changed: 30 ins; 5 del; 26 mod;

CTW might provoke <clinit> execution, some <clinit> (e.g. sun.tools.jconsole.OutputViewer[1]) can create new threads and hence cause CTW to hang. This fix updates CTW to call System::exit when all compilation tasks are completed. since jtreg does not like when tests call System::exit, testlibrary_tests/ctw tests have to be updated to start CTW from driver code rather than from jtreg test description.

JBS: https://bugs.openjdk.java.net/browse/JDK-8172149
webrev: http://cr.openjdk.java.net/~iignatyev/8172149/webrev.00/
testing: affected tests locally

[1] https://bugs.openjdk.java.net/browse/JDK-8159155

Thanks,
— Igor