jenkins: Only run journalctl if it is available on the machine

It's not common to run journald inside containers and the journalctl
command is not installed. Don't attempt to run it.

Change-Id: I9dee3cb0d0ca203da77dfa1a793a4e4e5f8593c6

contrib/jenkins-run.sh

@@ -30,7 +30,9 @@ rm -rf "$trial_dir/inst" || true
 
 # tar up all results for archiving (optional)
 cd "$trial_dir"
-journalctl -u ofono -o short-precise --since "${time_start}" > "$(readlink last_run)/ofono.log"
+if [ -x $(command -v journalctl) ]; then
+  journalctl -u ofono -o short-precise --since "${time_start}" > "$(readlink last_run)/ofono.log"
+fi
 tar czf "$base/${trial_dir}-run.tgz" "$(readlink last_run)"
 tar czf "$base/${trial_dir}-bin.tgz" *.md5 *.tgz