SLPVectorizer: Use use_empty instead of hasNUses(0) (llvm#137336)

Author: arsenm

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -16160,7 +16160,7 @@ Value *BoUpSLP::gather(
     } else {
       Vec = CreateShuffle(Root, Vec, Mask);
       if (auto *OI = dyn_cast<Instruction>(OriginalRoot);
-          OI && OI->hasNUses(0) &&
+          OI && OI->use_empty() &&
           none_of(VectorizableTree, [&](const std::unique_ptr<TreeEntry> &TE) {
             return TE->VectorizedValue == OI;
           }))