message: Add preferred generator for visual studio 2012.
diff: @@ -386,10 +386,12 @@ const VsArchitectures: {[key: string]: string} = {
  * Preferred CMake VS generators by VS version
  */
  const VsGenerators: {[key: string]: string} = {
  - 14: 'Visual Studio 14 2015',
  - 15: 'Visual Studio 15 2017',
  + 11: "Visual Studio 11 2012",
  VS120COMNTOOLS: 'Visual Studio 12 2013',
  + 12: "Visual Studio 12 2013",
  VS140COMNTOOLS: 'Visual Studio 14 2015',
  + 14: 'Visual Studio 14 2015',
  + 15: 'Visual Studio 15 2017'
  };
  async function varsForVSInstallation(inst: VSInstallation, arch: string): Promise<Map<string, string>|null> {
  