i#704: update a few pointer overflow checks
i#704: update a few pointer overflow checks

SVN-Revision: 2106

bl4ckic3/dynamorio,daksunt/dynamorio,bl4ckic3/dynamorio,sigma-random/dynamorio,AmesianX/dynamorio,code4bones/dynamorio,AmesianX/dynamorio,sigma-random/dynamorio,sigma-random/dynamorio,code4bones/dynamorio,daksunt/dynamorio,daksunt/dynamorio,bl4ckic3/dynamorio,bl4ckic3/dynamorio,code4bones/dynamorio,code4bones/dynamorio,AmesianX/dynamorio,sigma-random/dynamorio,code4bones/dynamorio,sigma-random/dynamorio,daksunt/dynamorio,AmesianX/dynamorio,daksunt/dynamorio,bl4ckic3/dynamorio,AmesianX/dynamorio