[gardening] Remove unused variable.

Author: gottesmm

lib/SILOptimizer/FunctionSignatureTransforms/ExistentialTransform.cpp

@@ -322,7 +322,6 @@ ExistentialTransform::createExistentialSpecializedFunctionType() {
   SILModule &M = F->getModule();
   auto &Ctx = M.getASTContext();
   GenericSignature NewGenericSig;
-  GenericEnvironment *NewGenericEnv;
 
   /// If the original function is generic, then maintain the same.
   auto OrigGenericSig = FTy->getInvocationGenericSignature();
@@ -341,8 +340,6 @@ ExistentialTransform::createExistentialSpecializedFunctionType() {
         std::move(Requirements)},
       GenericSignature());
 
-  NewGenericEnv = NewGenericSig->getGenericEnvironment();
-
   /// Create a lambda for GenericParams.
   auto getCanonicalType = [&](Type t) -> CanType {
     return t->getCanonicalType(NewGenericSig);