fix: event read from syslog

When labes map is too big we may get syslog entry truncated.
This breaks JSON parsing making event loading impossible.

[NO NEW TESTS NEEDED]

Signed-off-by: Matej Vasek <mvasek@redhat.com>

libpod/events/journal_linux.go

@@ -101,6 +101,10 @@ func (e EventJournalD) Read(ctx context.Context, options ReadOptions) error {
 			logrus.Errorf("Unable to close journal :%v", err)
 		}
 	}()
+	err = j.SetDataThreshold(640 * (1 << 10))
+	if err != nil {
+		logrus.Warnf("cannot set data threshold: %v", err)
+	}
 	// match only podman journal entries
 	podmanJournal := sdjournal.Match{Field: "SYSLOG_IDENTIFIER", Value: "podman"}
 	if err := j.AddMatch(podmanJournal.String()); err != nil {