RFR(XS): 8158756 - [Testbug] serviceability/dcmd/compiler/CompilerQueueTest.java fails with TieredStopAtLevel=1

[Dmitrij Pochepko]

Hi,

please review fix for 8158756 - [Testbug] 
serviceability/dcmd/compiler/CompilerQueueTest.java fails with 
TieredStopAtLevel=1

Test always failed when TieredStopAtLevel=1 flag was specified. A reason 
was that in case of -TieredCompilation and TieredStopAtLevel=1 
WhiteBox.enqueueMethodForCompilation returned false, because of 
respective check in code, indicating insuccessfull enqueue attempt. Test 
ignored this value previously assuming it's always true, so, I've 
modified test code to take returned value into account.

webrev: http://cr.openjdk.java.net/~dpochepk/8158756/webrev.01/
CR: https://bugs.openjdk.java.net/browse/JDK-8158756

I've tested this fix on linux-amd64 and linux-i586

Thanks,
Dmitrij