clang-tidy: fix `readability-redundant-access-specifiers` lints

Source/cmGlobalVisualStudioGenerator.h

@@ -193,7 +193,6 @@ protected:
   using UtilityDependsMap = std::map<cmGeneratorTarget const*, std::string>;
   UtilityDependsMap UtilityDepends;
 
-protected:
   VSVersion Version;
   bool ExpressEdition;
 

Source/cmVisualStudio10TargetGenerator.h

@@ -203,7 +203,6 @@ private:
   void WriteStdOutEncodingUtf8(Elem& e1);
   void UpdateCache();
 
-private:
   friend class cmVS10GeneratorOptions;
   using Options = cmVS10GeneratorOptions;
   using OptionsMap = std::map<std::string, std::unique_ptr<Options>>;