Choose correct name for platform

Author: alexey.gadzhiev

.appveyor.yml

@@ -23,6 +23,7 @@ init:
 - set arch=
 - if "%arch%"=="Win64" ( set arch= Win64)
 - echo %arch%
+- echo %PLATFORM%
 - echo %APPVEYOR_BUILD_WORKER_IMAGE%
 - if "%APPVEYOR_BUILD_WORKER_IMAGE%"=="Visual Studio 2017" ( set generator="Visual Studio 15 2017%arch%" )
 - if "%APPVEYOR_BUILD_WORKER_IMAGE%"=="Visual Studio 2015" ( set generator="Visual Studio 14 2015%arch%" )