[NFCI][SimplifyCFG] simplifyReturn(): use DeleteDeadBlock()

Author: LebedevRI

llvm/lib/Transforms/Utils/SimplifyCFG.cpp

@@ -4645,13 +4645,8 @@ bool SimplifyCFGOpt::simplifyReturn(ReturnInst *RI, IRBuilder<> &Builder) {
  }
 
  // If we eliminated all predecessors of the block, delete the block now.
- if (pred_empty(BB)) {
- // We know there are no successors, so just nuke the block.
- if (DTU)
- DTU->deleteBB(BB);
- else
- BB->eraseFromParent();
- }
+ if (pred_empty(BB))
+ DeleteDeadBlock(BB, DTU);
 
  return true;
  }