message: Add more kits to appveyor images
diff: @@ -40,19 +40,29 @@ const KITS_BY_PLATFORM: {[osName: string]: KitEnvironment[]} = {
  expectedDefaultGenerator: 'MinGW Makefiles',
  path: ['C:\\Program Files\\mingw-w64\\x86_64-7.2.0-posix-seh-rt_v5-rev1\\mingw64\\bin']
  }]),
  - ['Visual Studio 2017']: VISUAL_STUDIO_KITS.concat([{
  + ['Visual Studio 2017']: VISUAL_STUDIO_KITS.concat([
  + {
  defaultKit: 'GCC',
  expectedDefaultGenerator: 'MinGW Makefiles',
  path: ['C:\\mingw-w64\\x86_64-7.2.0-posix-seh-rt_v5-rev1\\mingw64\\bin']
  - }]),
  - ['Visual Studio 2017 Preview']: VISUAL_STUDIO_KITS.concat([]),
  + },
  + {defaultKit: 'GCC', expectedDefaultGenerator: 'Unix Makefiles', path: ['C:\\cygwin64\\bin']}
  + ]),
  + ['Visual Studio 2017 Preview']: VISUAL_STUDIO_KITS.concat(
  + [{defaultKit: 'GCC', expectedDefaultGenerator: 'Unix Makefiles', path: ['C:\\cygwin64\\bin']}]),
  ['Visual Studio 2015']: VISUAL_STUDIO_KITS.concat([
  + {
  + defaultKit: 'GCC',
  + expectedDefaultGenerator: 'MinGW Makefiles',
  + path: ['C:\\mingw-w64\\x86_64-7.2.0-posix-seh-rt_v5-rev1\\mingw64\\bin']
  + },
  {
  defaultKit: 'GCC',
  expectedDefaultGenerator: 'MinGW Makefiles',
  path: ['C:\\mingw-w64\\x86_64-6.3.0-posix-seh-rt_v5-rev1\\mingw64\\bin']
  },
  - {defaultKit: 'GCC', expectedDefaultGenerator: 'MinGW Makefiles', path: ['C:\\MinGW\\bin']}
  + {defaultKit: 'GCC', expectedDefaultGenerator: 'MinGW Makefiles', path: ['C:\\MinGW\\bin']},
  + {defaultKit: 'GCC', expectedDefaultGenerator: 'Unix Makefiles', path: ['C:\\cygwin64\\bin']}
  ]),
  ['linux']: [
  {defaultKit: 'Clang', expectedDefaultGenerator: 'Unix Makefiles'},
  