[clang][dataflow][NFC] Resize vector directly with ctor

clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp

runTypeErasedDataflowAnalysis(
     const ControlFlowContext &CFCtx, TypeErasedDataflowAnalysis &Analysis,
     const Environment &InitEnv,
     std::function<void(const CFGStmt &,
                        const TypeErasedDataflowAnalysisState &)>
         PostVisitStmt) {
   PostOrderCFGView POV(&CFCtx.getCFG());
   ForwardDataflowWorklist Worklist(CFCtx.getCFG(), &POV);
 
-  std::vector<llvm::Optional<TypeErasedDataflowAnalysisState>> BlockStates;
-  BlockStates.resize(CFCtx.getCFG().size(), llvm::None);
+  std::vector<llvm::Optional<TypeErasedDataflowAnalysisState>> BlockStates(
+      CFCtx.getCFG().size(), llvm::None);
 
   // The entry basic block doesn't contain statements so it can be skipped.
   const CFGBlock &Entry = CFCtx.getCFG().getEntry();
   BlockStates[Entry.getBlockID()] = {Analysis.typeErasedInitialElement(),
                                      InitEnv};
   Worklist.enqueueSuccessors(&Entry);
 
   // Bugs in lattices and transfer functions can prevent the analysis from