Fix for too many open files in rocrtst

Fix for regression in commit:
8a0fe6a832

When running rocrtstNeg.Queue_Validation_InvalidWorkGroupSize, each
time rocrtst::LoadKernelFromObjFile is called, a new CodeObject is
created and not deleted until end of the whole test. Each CodeObject
keeps an open file descriptor of the kernel file and this can exceed
maximum allowed open files on some systems. Deleting the CodeObjects
after each iteration in the test.

Change-Id: I388e56f95f7b671ecc29d5ecb4eb8ac2d0ddc412

rocrtst/suites/negative/queue_validation.cc

@@ -577,6 +577,7 @@ void QueueValidation::QueueValidationForInvalidWorkGroupSize(hsa_agent_t cpuAgen
 
       hsa_signal_store_relaxed(aql().completion_signal, 1);
       if (queue[ii]) { hsa_queue_destroy(queue[ii]); }
+      clear_code_object();
     }
   }
   sleep(1);