RFR(S): 8158650 - [jittester] when generating tests with default parameters, generation hangs after 98 test

[Dmitrij Pochepko]

Hi all,

please review fix for 8158650 - [jittester] when generating tests with 
default parameters, generation hangs after 98 test

Jittester had a few loops conditions which caused infinite looping in 
special corner cases(case of too simple code without blocks and case of 
too complex code with large depth). I've re-organize respective loops 
code to have it fixed.

webrev: http://cr.openjdk.java.net/~dpochepk/8158650/webrev.01/
CR: https://bugs.openjdk.java.net/browse/JDK-8158650

I've verified fix locally on linux-amd64.

Thanks,
Dmitrij