STYLE: fix warning

Source/cmGlobalVisualStudioGenerator.cxx

@@ -709,7 +709,6 @@ bool cmGlobalVisualStudioGenerator::TargetIsFortranOnly(cmTarget& target)
   // check to see if this is a fortran build
   std::set<cmStdString> languages;
   target.GetLanguages(languages);
-  const char* ext = ".vcproj";
   if(languages.size() == 1)
     {
     if(*languages.begin() == "Fortran")