CMake generates wrong Visual Studio projects for C# targets when AUTOMOC is on

On a CMake project mixing C++ and C# targets, if AUTOMOC is on, CMake will automatically generate mocs_compilation.cpp for all C# targets, as cmQtAutoGenGlobalInitializer::cmQtAutoGenGlobalInitializer doesn't filter out non C++ projects for moc generation. At that point cmGeneratorTarget::IsCSharpOnly() will return false on C# targets (the languages for the targets will be "CXX" and "CSharp"), CMake generates a vcxproj file instead of a csproj file for them, and the build fails.