QPID: Additional queue NULL checks.
QPID: Additional queue NULL checks.

Add further NULL checks to the QPID queue implementation based on
unit test results.

Signed-off-by: Damian Maguire <21930bd10afdadbc1f53edcd2634e8f66a5e6d7a@nyx.com>

jacobraj/MAMA,fquinner/OpenMAMA,MattMulhern/OpenMamaCassandra,dmaguire/OpenMAMA,MattMulhern/OpenMamaCassandra,philippreston/OpenMAMA,MattMulhern/OpenMamaCassandra,philippreston/OpenMAMA,MattMulhern/OpenMamaCassandra,MattMulhern/OpenMAMA,MattMulhern/OpenMAMA,dmagOM/OpenMAMA-dynamic,dmagOM/OpenMAMA-dynamic,kuangtu/OpenMAMA,dpauls/OpenMAMA,dmaguire/OpenMAMA,jacobraj/MAMA,vulcanft/openmama,jacobraj/MAMA,dpauls/OpenMAMA,jacobraj/MAMA,MattMulhern/OpenMAMA,dpauls/OpenMAMA,cloudsmith-io/openmama,vulcanft/openmama,fquinner/OpenMAMA,MattMulhern/OpenMAMA,vulcanft/openmama,dmagOM/OpenMAMA-dynamic,dpauls/OpenMAMA,kuangtu/OpenMAMA,dmagOM/OpenMAMA-dynamic,MattMulhern/OpenMAMA,dmagOM/OpenMAMA-dynamic,philippreston/OpenMAMA,dmaguire/OpenMAMA,kuangtu/OpenMAMA,jacobraj/MAMA,kuangtu/OpenMAMA,cloudsmith-io/openmama,fquinner/OpenMAMA,dmaguire/OpenMAMA,MattMulhern/OpenMAMA,dpauls/OpenMAMA,dmagOM/OpenMAMA-dynamic,kuangtu/OpenMAMA,fquinner/OpenMAMA,cloudsmith-io/openmama,vulcanft/openmama,MattMulhern/OpenMAMA,dmaguire/OpenMAMA,dpauls/OpenMAMA,kuangtu/OpenMAMA,cloudsmith-io/openmama,vulcanft/openmama,cloudsmith-io/openmama,vulcanft/openmama,fquinner/OpenMAMA,vulcanft/openmama,philippreston/OpenMAMA,MattMulhern/OpenMamaCassandra,philippreston/OpenMAMA,dpauls/OpenMAMA,fquinner/OpenMAMA,cloudsmith-io/openmama,cloudsmith-io/openmama,kuangtu/OpenMAMA,dmaguire/OpenMAMA,dmaguire/OpenMAMA,MattMulhern/OpenMamaCassandra,fquinner/OpenMAMA,philippreston/OpenMAMA,philippreston/OpenMAMA,jacobraj/MAMA