[clang][dataflow] Remove unused private field 'StmtToEnv' (NFC)

llvm-project/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp:148:23:
 error: private field 'StmtToEnv' is not used [-Werror,-Wunused-private-field]
  148 |   const StmtToEnvMap &StmtToEnv;
      |                       ^
1 error generated.

Author: DamonFool

clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp

@@ -77,7 +77,7 @@ class TerminatorVisitor
 public:
   TerminatorVisitor(const StmtToEnvMap &StmtToEnv, Environment &Env,
                     int BlockSuccIdx)
-      : StmtToEnv(StmtToEnv), Env(Env), BlockSuccIdx(BlockSuccIdx) {}
+      : Env(Env), BlockSuccIdx(BlockSuccIdx) {}
 
   TerminatorVisitorRetTy VisitIfStmt(const IfStmt *S) {
     auto *Cond = S->getCond();
@@ -145,7 +145,6 @@ class TerminatorVisitor
     return {&Cond, ConditionValue};
   }
 
-  const StmtToEnvMap &StmtToEnv;
   Environment &Env;
   int BlockSuccIdx;
 };