Add Windows 1809 images to AppVeyor configuration

Author: tianon

.appveyor.yml

@@ -5,12 +5,22 @@ environment:
   matrix:
     - version: 4.2
       variant: windowsservercore-ltsc2016
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+    - version: 4.2
+      variant: windowsservercore-1809
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
     - version: 4.0
       variant: windowsservercore-ltsc2016
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+    - version: 4.0
+      variant: windowsservercore-1809
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
     - version: 3.6
       variant: windowsservercore-ltsc2016
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
     - version: 3.4
       variant: windowsservercore-ltsc2016
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
 
 install:
   - ps: |

update.sh

@@ -150,8 +150,13 @@ for version in "${versions[@]}"; do
 			fi
 
 			case "$winVariant" in
-				*-1809) ;; # no AppVeyor or Travis support for 1809: https://github.com/appveyor/ci/issues/1885
-				*) appveyorEnv='\n    - version: '"$version"'\n      variant: '"$winVariant$appveyorEnv" ;;
+				# https://www.appveyor.com/docs/windows-images-software/
+				*-1809)
+					appveyorEnv='\n    - version: '"$version"'\n      variant: '"$winVariant"'\n      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019'"$appveyorEnv"
+					;;
+				*-ltsc2016)
+					appveyorEnv='\n    - version: '"$version"'\n      variant: '"$winVariant"'\n      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017'"$appveyorEnv"
+					;;
 			esac
 		done
 	fi