Fix compiler warning

Fix the following warning, as any warning will be treated as error
../../../dump_utils.hpp:38:9: warning: Value stored to 'event' is never read

event = sd_event_unref(event);

Change-Id: I020c2b2028e19ce8998754a38cb55830792a0118
Signed-off-by: Deepa Karthikeyan <deepakala.karthikeyan@ibm.com>
diff --git a/dump_utils.hpp b/dump_utils.hpp
index 27aefef..1b86575 100644
--- a/dump_utils.hpp
+++ b/dump_utils.hpp
@@ -35,7 +35,7 @@
 {
     void operator()(sd_event* event) const
     {
-        event = sd_event_unref(event);
+        sd_event_unref(event);
     }
 };
 using EventPtr = std::unique_ptr<sd_event, EventDeleter>;