[clang][dataflow][NFC] Remove unused parameter from `insertIfGlobal()`.

clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp

if (auto *W = Model.widen(Type, Prev, PrevEnv, Current, CurrentEnv))
     return *W;
 
   // Default of widening is a no-op: leave the current value unchanged.
   return Current;
 }
 
 /// Initializes a global storage value.
 static void insertIfGlobal(const Decl &D,
-                           llvm::DenseSet<const FieldDecl *> &Fields,
                            llvm::DenseSet<const VarDecl *> &Vars) {
   if (auto *V = dyn_cast<VarDecl>(&D))
     if (V->hasGlobalStorage())
       Vars.insert(V);
 }
 
 static void getFieldsAndGlobalVars(const Decl &D,
                                    llvm::DenseSet<const FieldDecl *> &Fields,
                                    llvm::DenseSet<const VarDecl *> &Vars) {
-  insertIfGlobal(D, Fields, Vars);
+  insertIfGlobal(D, Vars);
   if (const auto *Decomp = dyn_cast<DecompositionDecl>(&D))
     for (const auto *B : Decomp->bindings())
       if (auto *ME = dyn_cast_or_null<MemberExpr>(B->getBinding()))
         // FIXME: should we be using `E->getFoundDecl()`?
         if (const auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl()))
           Fields.insert(FD);
 }
 
 /// Traverses `S` and inserts into `Vars` any global storage values that are
 /// declared in or referenced from sub-statements.
 static void getFieldsAndGlobalVars(const Stmt &S,
                                    llvm::DenseSet<const FieldDecl *> &Fields,
                                    llvm::DenseSet<const VarDecl *> &Vars) {
   for (auto *Child : S.children())
     if (Child != nullptr)
       getFieldsAndGlobalVars(*Child, Fields, Vars);
 
   if (auto *DS = dyn_cast<DeclStmt>(&S)) {
     if (DS->isSingleDecl())
       getFieldsAndGlobalVars(*DS->getSingleDecl(), Fields, Vars);
     else
       for (auto *D : DS->getDeclGroup())
           getFieldsAndGlobalVars(*D, Fields, Vars);
   } else if (auto *E = dyn_cast<DeclRefExpr>(&S)) {
-    insertIfGlobal(*E->getDecl(), Fields, Vars);
+    insertIfGlobal(*E->getDecl(), Vars);
   } else if (auto *E = dyn_cast<MemberExpr>(&S)) {
     // FIXME: should we be using `E->getFoundDecl()`?
     const ValueDecl *VD = E->getMemberDecl();
-    insertIfGlobal(*VD, Fields, Vars);
+    insertIfGlobal(*VD, Vars);
     if (const auto *FD = dyn_cast<FieldDecl>(VD))
       Fields.insert(FD);
   }
 }
 
 // FIXME: Add support for resetting globals after function calls to enable
 // the implementation of sound analyses.
 void Environment::initFieldsAndGlobals(const FunctionDecl *FuncDecl) {