[NVPTX] Don't (incorrectly) say that the NVVMReflect pass preserves all analyses.

[jlebar]

I am pretty confident that this is a correctness fix, so going with post-commit review here.

llvm/trunk/lib/Target/NVPTX/NVVMReflect.cpp

public:
   NVVMReflect() : NVVMReflect(StringMap<int>()) {}
 
   NVVMReflect(const StringMap<int> &Mapping)
       : FunctionPass(ID), VarMap(Mapping) {
     initializeNVVMReflectPass(*PassRegistry::getPassRegistry());
     setVarMap();
   }
 
-  void getAnalysisUsage(AnalysisUsage &AU) const override {
-    AU.setPreservesAll();
-  }
   bool runOnFunction(Function &) override;
 
 private:
   bool handleFunction(Function *ReflectFunction);
   void setVarMap();
 };
 }