Revert "Revert "appveyor: turn on RDP""

This reverts commit b775765581.

appveyor.yml

@@ -8,6 +8,7 @@ init:
   - set MSYSTEM=MINGW64
   - pacman --noconfirm --needed -S mingw-w64-x86_64-toolchain mingw-w64-x86_64-cmake
   - set "PATH=%PATH%;%APPVEYOR_BUILD_FOLDER%\build;%APPVEYOR_BUILD_FOLDER%\build\Debug;%APPVEYOR_BUILD_FOLDER%\build\external\bin;%APPVEYOR_BUILD_FOLDER%\build\external\lib"
+  - ps: iex ((new-object net.webclient).DownloadString('https://raw.githubusercontent.com/appveyor/ci/master/scripts/enable-rdp.ps1')) 
 
 environment:
   COVERALLS_REPO_TOKEN:
@@ -90,6 +91,9 @@ test_script:
             $host.setshouldexit(1)
         }
 
+on_finish:
+  - ps: $blockRdp = $true; iex ((new-object net.webclient).DownloadString('https://raw.githubusercontent.com/appveyor/ci/master/scripts/enable-rdp.ps1')) 
+
 #after_test:
 #  - 'make coveralls'