CircleCI: Display Appimage log when failing

.circleci/config.yml

@@ -100,7 +100,7 @@ jobs:
           command: |
             cd build
             make install
-            make appimage
+            make appimage || cat appimage.log
             cp ./lmms-*.AppImage /tmp/artifacts/
       - store_artifacts:
           path: /tmp/artifacts/