Correct replication origin's use of UINT16_MAX to PG_UINT16_MAX.

We can't rely on UINT16_MAX being present, which is why we introduced
PG_UINT16_MAX...

Buildfarm animal bowerbird via Andrew Gierth.

src/backend/replication/logical/origin.c

@@ -266,7 +266,7 @@ replorigin_create(char *roname)
 
 	rel = heap_open(ReplicationOriginRelationId, ExclusiveLock);
 
-	for (roident = InvalidOid + 1; roident < UINT16_MAX; roident++)
+	for (roident = InvalidOid + 1; roident < PG_UINT16_MAX; roident++)
 	{
 		bool		nulls[Natts_pg_replication_origin];
 		Datum		values[Natts_pg_replication_origin];

src/include/replication/origin.h

@@ -30,7 +30,7 @@ typedef struct xl_replorigin_drop
 #define XLOG_REPLORIGIN_DROP		0x10
 
 #define InvalidRepOriginId 0
-#define DoNotReplicateId UINT16_MAX
+#define DoNotReplicateId PG_UINT16_MAX
 
 extern PGDLLIMPORT RepOriginId replorigin_sesssion_origin;
 extern PGDLLIMPORT XLogRecPtr replorigin_sesssion_origin_lsn;