AppVeyor: Deploy artifacts to Amazon S3

We would have been perfectly happy for AppVeyor to delete all artifacts
other than those from the latest builds in each branch.  Instead, they
chose to change the global artifact retention policy to 1 month.  In
addition to being unworkable, that new policy uses more storage than the
policy we requested.  Lose/lose, so we'll just deploy to S3 like we do
with other platforms.

appveyor.yml

@@ -51,6 +51,8 @@ build_script:
 
       move c:\ljt.nightly\files\*.exe .
 
+      move c:\ljt.nightly\files\*.html .
+
       move c:\ljt.nightly\log-windows.txt .
 
 artifacts:
@@ -66,6 +68,20 @@ artifacts:
   - path: 'log-windows.txt'
     name: Build log
 
+  - path: 'index.html'
+    name: MD5 checksums
+
 test: off
 
-deploy: off
+deploy:
+  provider: S3
+  access_key_id:
+    secure: Z74OYogQ6bNV/I+6b5ZEXig74+6MW2WLER0v/bPM/uk=
+  secret_access_key:
+    secure: cyGZhHVCFwZ9jgf5lXoW69mVtECmqwx3eLo61ha8ueWbMYlHho7lwDXwVvxOFiCa
+  bucket: libjpeg-turbo-pr
+  region:
+    secure: qSElYBgBRcEUf88M6Osthw==
+  folder: $(APPVEYOR_REPO_BRANCH)/windows
+  set_public: true
+  remove_files: true