Use DatumGetInt32() to extract 32-bit integer value from a datum.

Previously DatumGetObjectId() was wrongly used for that.

Author: Masahiko Sawada
Reviewed-by: Kyotaro Horiguchi
Reported-by: Fujii Masao
Discussion: http://postgr.es/m/CAHGQGwFDWh_Qr-q_GEMpD+qH=vYPMdVqw=ZOSY3kX_Pna9R9SA@mail.gmail.com

src/backend/replication/logical/launcher.c

@@ -306,7 +306,7 @@ logicalrep_worker_launch(Oid dbid, Oid subid, const char *subname, Oid userid,
 
 	bgw.bgw_restart_time = BGW_NEVER_RESTART;
 	bgw.bgw_notify_pid = MyProcPid;
-	bgw.bgw_main_arg = slot;
+	bgw.bgw_main_arg = Int32GetDatum(slot);
 
 	if (!RegisterDynamicBackgroundWorker(&bgw, &bgw_handle))
 	{

src/backend/replication/logical/worker.c

@@ -1441,7 +1441,7 @@ subscription_change_cb(Datum arg, int cacheid, uint32 hashvalue)
 void
 ApplyWorkerMain(Datum main_arg)
 {
-	int				worker_slot = DatumGetObjectId(main_arg);
+	int				worker_slot = DatumGetInt32(main_arg);
 	MemoryContext	oldctx;
 	char			originname[NAMEDATALEN];
 	XLogRecPtr		origin_startpos;