docker_appimage_tests.sh: print which test failed

Since the tests are run in parallel (and also there is much output),
it may be difficult to track which one container actually failed so
write at least a summary.

Author: MartinPulec

.github/scripts/Linux/docker_appimage_tests.sh

@@ -1,5 +1,7 @@
 #!/bin/sh -eu
 
+echo "Starting Docker AppImage tests..." >&2
+
 mkdir aitest-context # empty build context
 ./UltraGrid-"$VERSION"-x86_64.AppImage --appimage-extract
 
@@ -27,7 +29,19 @@ for n in $test_list; do
         name=$(printf "%s" "$n" | tr -c '[:alnum:]' '[_*]') # replace :. with _ for valid identifer
         eval "${name}_pid"=$!
 done
+
+set +e
+rc=0
 for n in $test_list; do
         name=$(printf "%s" "$n" | tr -c '[:alnum:]' '[_*]')
-        eval wait "\$${name}_pid"
+        if eval wait "\$${name}_pid"; then
+                echo "Docker AppImage test $name succeeded" >&2
+        else
+                rc=$?
+                echo "Docker AppImage test $name FAILED with error code $rc" >&2
+        fi
 done
+if [ $rc -ne 0 ]; then
+        exit $rc
+fi
+echo "All Docker AppImage tests succeeded" >&2