[OO] Fixed PMC_IS_NULL() check to check the right PMC (see r31966 and r31974).
[OO] Fixed PMC_IS_NULL() check to check the right PMC (see r31966 and r31974).

git-svn-id: 6e74a02f85675cec270f5d931b0f6998666294a3@31978 d31e2699-5ff4-0310-a27c-f18f2fbe73fe

ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot