RFR(M) : 8251132 : make main classes public in vmTestbase/jit tests

[Igor Ignatyev]

http://cr.openjdk.java.net/~iignatyev//8251132/webrev.00
> 498 lines changed: 0 ins; 132 del; 366 mod;

Hi all,

could you please review the patch which adds public modifier to "main" test classes in vmTestbase/jit tests?
from JBS:
> main test classes of several vmTestbase/jit tests are package-private, as a result, jtreg can't run them directly and we had to use `driver ExecDriver --java ` to run them. 
> 
> this RFE is to make these classes public and to replace ExecDriver w/ regular `main/othervm` where appropriate.

the patch also removes ExecDriver and @build in all but 6 tests. those 6 (vmTestbase/jit/t/t108--t113) compare stack traces to the golden ones, and execution them "directly" by jtreg will lead to failures due to a few extra frames from jtreg.

JBS: https://bugs.openjdk.java.net/browse/JDK-8251132
testing: :vmTestbase_vm_compiler on {linux,windows,macos}-x64
webrev: http://cr.openjdk.java.net/~iignatyev//8251132/webrev.00

Thanks,
-- Igor