JDK6: fix iiop tests

Getting errors like this when running the iiop tests:

java.rmi.RemoteException: CORBA BAD_INV_ORDER 4 No; nested exception is:
org.omg.CORBA.BAD_INV_ORDER: vmcid: 0x0 minor code: 4 completed: No
at com.sun.corba.se.impl.javax.rmi.CORBA.Util.mapSystemException(Util.java:282)
at javax.rmi.CORBA.Util.mapSystemException(Util.java:67)
at org.jboss.proxy.ejb.DynamicIIOPStub.invoke(DynamicIIOPStub.java:148)
at org.jboss.test.excepiiop.interfaces._ExceptionThrower_Stub.throwException(Unknown Source)
at org.jboss.test.excepiiop.test.ExceptionTimingStressTestCase.testSpeedJavaException(ExceptionTimingStressTestCase.java:146)
at junit.extensions.TestDecorator.basicRun(TestDecorator.java:24)
at junit.extensions.TestSetup$1.protect(TestSetup.java:21)
at junit.extensions.TestSetup.run(TestSetup.java:25)
Caused by: org.omg.CORBA.BAD_INV_ORDER: vmcid: 0x0 minor code: 4 completed: No
at org.jacorb.orb.ORB.work_pending(Unknown Source)
at org.jacorb.orb.ORB.perform_work(Unknown Source)
at org.jacorb.orb.Delegate.request(Unknown Source)
at org.omg.CORBA.portable.ObjectImpl._request(ObjectImpl.java:431)
at org.jboss.proxy.ejb.DynamicIIOPStub.invoke(DynamicIIOPStub.java:119)
... 23 more

This is reported as a bug in Sun JDK 1.6. See JBAS-5482.