simplify appveyor config

appveyor.yml

@@ -6,43 +6,38 @@ environment:
   matrix:
     # Visual Studio 2019 64bit
     - visualcpp: C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvars64.bat
-      os: Visual Studio 2019
+      appveyor_build_worker_image: Visual Studio 2019
 
     # Visual Studio 2019 32bit
     - visualcpp: C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvars32.bat
-      os: Visual Studio 2019
-      machine: x86
+      appveyor_build_worker_image: Visual Studio 2019
 
     # Visual Studio 2017 64bit
     - visualcpp: C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Auxiliary\Build\vcvars64.bat
-      os: Visual Studio 2017
+      appveyor_build_worker_image: Visual Studio 2017
 
     # Visual Studio 2017 32bit
-    - visualcpp: C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Auxiliary\Build\vcvarsall.bat
-      os: Visual Studio 2017
-      machine: x86
+    - visualcpp: C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Auxiliary\Build\vcvars32.bat
+      appveyor_build_worker_image: Visual Studio 2017
 
     # Visual Studio 2015 64bit
-    - visualcpp: C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat
-      os: Visual Studio 2015
-      machine: amd64
+    - visualcpp: C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvars64.bat
+      appveyor_build_worker_image: Visual Studio 2015
 
     # Visual Studio 2015 32bit
-    - visualcpp: C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat
-      os: Visual Studio 2015
-      machine: x86
+    - visualcpp: C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvars32.bat
+      appveyor_build_worker_image: Visual Studio 2015
 
     # Visual Studio 2013 64bit
-    - visualcpp: C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\vcvarsall.bat
-      os: Visual Studio 2013
-      machine: amd64
+    - visualcpp: C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\vcvars64.bat
+      appveyor_build_worker_image: Visual Studio 2013
 
     # Visual Studio 2013 32bit
-    - visualcpp: C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\vcvarsall.bat
-      os: Visual Studio 2013
-      machine: x86
+    - visualcpp: C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\vcvars32.bat
+      appveyor_build_worker_image: Visual Studio 2013
+
 init:
-  - call "%visualcpp%" %machine%
+  - call "%visualcpp%"
   # For using Rubyins4aller's Ruby 2.6 64bit
   # 2.6 is the highest supported Ruby version across all historical
   # Visual Studio AppVeyor images. Ruby 2.7 is only on the 2019 image.