Fix relcache reference leak introduced by ce0fdbfe97.

Author: Sawada Masahiko
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/CAD21AoA7ZEfsOXQ9HQqMv3QYGsEm2H5Wk5ic5S=mvzDf-3a3SA@mail.gmail.com

src/backend/catalog/pg_subscription.c

@@ -353,6 +353,7 @@ GetSubscriptionRelState(Oid subid, Oid relid, XLogRecPtr *sublsn)
 
 	if (!HeapTupleIsValid(tup))
 	{
+		table_close(rel, AccessShareLock);
 		*sublsn = InvalidXLogRecPtr;
 		return SUBREL_STATE_UNKNOWN;
 	}