[ProcessImplicitDefs] Enable machine verification after this pass

[foad]

Summary

Enabling this does not show any problems in check-llvm in an
LLVM_ENABLE_EXPENSIVE_CHECKS build.

[MatzeB]

I'm always happy when we can cover more parts of CodeGen with the machine verifier. Let's hope this sticks. LGTM

llvm/lib/CodeGen/TargetPassConfig.cpp

 }
 
 /// Add standard target-independent passes that are tightly coupled with
 /// optimized register allocation, including coalescing, machine instruction
 /// scheduling, and register allocation itself.
 void TargetPassConfig::addOptimizedRegAlloc() {
   addPass(&DetectDeadLanesID);
 
-  addPass(&ProcessImplicitDefsID, false);
+  addPass(&ProcessImplicitDefsID);
 
   // LiveVariables currently requires pure SSA form.
   //
   // FIXME: Once TwoAddressInstruction pass no longer uses kill flags,
   // LiveVariables can be removed completely, and LiveIntervals can be directly
   // computed. (We still either need to regenerate kill flags after regalloc, or
   // preferably fix the scavenger to not depend on them).
   // FIXME: UnreachableMachineBlockElim is a dependant pass of LiveVariables.