Search for something which doesn't exist so we get the full output

Author: vmcj

.github/jobs/configure-checks/all.bats

@@ -433,6 +433,7 @@ compile_assertions_finished () {
   assert_line " * judgehost...........: /opt/domjudge/judgehost"
   assert_line " * runguard group......: domjudge-run"
   run make domserver
+  assert_line "Show output"
   assert_success
   run make judgehost
   assert_success