improved exception testing

cMIPS/tests/badVAddr.expected

cMIPS/tests/badVAddr.s

cMIPS/tests/badVAddrMM.expected

cMIPS/tests/badVAddrMM.s

cMIPS/tests/counter.expected

cMIPS/tests/counter.s

cMIPS/tests/doTests.sh

cMIPS/tests/mmu_double.s

cMIPS/tests/mmu_double2.s

cMIPS/tests/mmu_inval.s

cMIPS/tests/mmu_inval2.s

cMIPS/tests/mmu_mod.s

cMIPS/tests/mmu_mod2.s

cMIPS/tests/mmu_refill.s

cMIPS/tests/mmu_refill2.s

cMIPS/tests/mmu_refill3.s