events: Remove ATTRIBUTE_NONNULL for virObjectEventStateQueue[Remote]

Commit aad3a0b5 altered virObjectEventStateQueueRemote to move
the "if (!event) return" call added in the previous commit 031eb8f6
to virObjectEventStateQueue. Neither commit altered the function
prototype which used ATTRIBUTE_NONNULL(2).

This caused Coverity build problems. Since @event is now checked,
just remove the ATTRIBUTE_NONNULL check from both prototypes.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

src/conf/object_event.h

@@ -62,13 +62,13 @@ typedef void (*virConnectObjectEventGenericCallback)(virConnectPtr conn,
 void
 virObjectEventStateQueue(virObjectEventStatePtr state,
                          virObjectEventPtr event)
-    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
+    ATTRIBUTE_NONNULL(1);
 
 void
 virObjectEventStateQueueRemote(virObjectEventStatePtr state,
                                virObjectEventPtr event,
                                int remoteID)
-    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
+    ATTRIBUTE_NONNULL(1);
 
 int
 virObjectEventStateDeregisterID(virConnectPtr conn,