[SCCP] Preserve Name when converting SExt->ZExt.

[craig.topper]

Summary

This makes the output IR more readable since we're doing a one to
one replacement.

[fhahn]

LGTM, thanks!

llvm/lib/Transforms/Scalar/SCCP.cpp

if (tryToReplaceWithConstant(Solver, &Inst)) {
       Value *ExtOp = Inst.getOperand(0);
       if (isa<Constant>(ExtOp) || InsertedValues.count(ExtOp))
         continue;
       const ValueLatticeElement &IV = Solver.getLatticeValueFor(ExtOp);
       if (!IV.isConstantRange(/*UndefAllowed=*/false))
         continue;
       if (IV.getConstantRange().isAllNonNegative()) {
         auto *ZExt = new ZExtInst(ExtOp, Inst.getType(), "", &Inst);
+        ZExt->takeName(&Inst);
         InsertedValues.insert(ZExt);
         Inst.replaceAllUsesWith(ZExt);
         Solver.removeLatticeValueFor(&Inst);
         Inst.eraseFromParent();
         InstReplacedStat++;
         MadeChanges = true;
       }
     }