Appveyor: always show the logs, and upload them as build artifacts

Always show the configure and test logs, and upload them as build
artifacts, when building for Windows using Appveyor CI.

Implements 28459.

.appveyor.yml

@@ -60,7 +60,7 @@ test_script:
             Execute-Bash "VERBOSE=1 make -j2 check"
     }
 
-on_failure:
+on_finish:
 - ps: >-
     if ($env:compiler -eq "mingw") {
             $oldpath = ${env:Path} -split ';'
@@ -73,4 +73,6 @@ on_failure:
             Execute-Bash "tail -1000 config.log || true"
             Execute-Bash "cat test-suite.log || true"
     }
+
+on_failure:
 - cmd: C:\Python27\python.exe %APPVEYOR_BUILD_FOLDER%\scripts\test\appveyor-irc-notify.py irc.oftc.net:6697 tor-ci failure

changes/ticket28459

@@ -0,0 +1,4 @@
+  o Minor features (continuous integration, Windows):
+    - Always show the configure and test logs, and upload them as build
+      artifacts, when building for Windows using Appveyor CI.
+      Implements 28459.