cmake: Constify cmake::GetRegisteredGenerators

Source/cmake.cxx

@@ -811,7 +811,8 @@ void cmake::AddDefaultExtraGenerators()
 #endif
 }
 
-void cmake::GetRegisteredGenerators(std::vector<GeneratorInfo>& generators)
+void cmake::GetRegisteredGenerators(
+  std::vector<GeneratorInfo>& generators) const
 {
   for (RegisteredGeneratorsVector::const_iterator i = this->Generators.begin(),
                                                   e = this->Generators.end();

Source/cmake.h

@@ -187,7 +187,7 @@ public:
   void SetGlobalGenerator(cmGlobalGenerator*);
 
   ///! Get the names of the current registered generators
-  void GetRegisteredGenerators(std::vector<GeneratorInfo>& generators);
+  void GetRegisteredGenerators(std::vector<GeneratorInfo>& generators) const;
 
   ///! Set the name of the selected generator-specific platform.
   void SetGeneratorPlatform(std::string const& ts)