Appveyor: Update to 2019 image

Author: larskanis

.appveyor.yml

@@ -1,12 +1,16 @@
+image: Visual Studio 2019
+
 install:
-  - SET PATH=C:/Ruby%ruby_version%/bin;%PATH%
-  - SET RAKEOPT=-rdevkit
+  - set PATH=C:/Ruby%ruby_version%/bin;c:/Program Files/Git/cmd;c:/Windows/system32;C:/Windows/System32/WindowsPowerShell/v1.0;C:/Program Files/Mercurial
+  - set RAKEOPT=-rdevkit
+  - set RUBYOPT=--verbose
   - ps: |
       if ($env:ruby_version -like "*head*") {
         $(new-object net.webclient).DownloadFile("https://github.com/oneclick/rubyinstaller2/releases/download/rubyinstaller-head/rubyinstaller-$env:ruby_version.exe", "$pwd/ruby-setup.exe")
         cmd /c ruby-setup.exe /verysilent /dir=C:/Ruby$env:ruby_version
       }
-  - ruby --version
+  - ridk version
+  - ridk exec sh -c "pacman -S --noconfirm --needed ${MINGW_PACKAGE_PREFIX}-gcc"
   - gem --version
   - bundle install