Enable verifier after PeepholeOptimizer

No tests fail with this enabled so I assume it was an accident
that it isn't enabled now.

llvm-svn: 250070

llvm/lib/CodeGen/Passes.cpp

@@ -633,7 +633,7 @@ void TargetPassConfig::addMachineSSAOptimization() {
   addPass(&MachineCSEID, false);
   addPass(&MachineSinkingID);
 
-  addPass(&PeepholeOptimizerID, false);
+  addPass(&PeepholeOptimizerID);
   // Clean-up the dead code that may have been generated by peephole
   // rewriting.
   addPass(&DeadMachineInstructionElimID);