I'm not fully confident if it might break other platforms. So hopefully 
someone can comment on the patch.

gcc/testsuite/ChangeLog:

         * c-c++-common/Wsizeof-array-div1.c: fix excess warnings.
         * gcc.dg/Warray-bounds-52.c: ditto
         * gcc.dg/Wstringop-overflow-62.c: ditto
         * gcc.dg/attr-vector_size.c: ditto
         * gcc.dg/overflow-warn-9.c: ditto

Comments?