Fix typos.

Author: Naoki Nakamichi
Discussion: https://postgr.es/m/b6919d145af00295a8e86ce4d034b7cd@oss.nttdata.com

src/backend/storage/ipc/procarray.c

@@ -4106,7 +4106,7 @@ GlobalVisCheckRemovableXid(Relation rel, TransactionId xid)
  *
  * Be very careful about when to use this function. It can only safely be used
  * when there is a guarantee that xid is within MaxTransactionId / 2 xids of
- * rel. That e.g. can be guaranteed if the the caller assures a snapshot is
+ * rel. That e.g. can be guaranteed if the caller assures a snapshot is
  * held by the backend and xid is from a table (where vacuum/freezing ensures
  * the xid has to be within that range), or if xid is from the procarray and
  * prevents xid wraparound that way.

src/backend/utils/time/snapmgr.c

@@ -1855,7 +1855,7 @@ TransactionIdLimitedForOldSnapshots(TransactionId recentXmin,
 		if (ts == threshold_timestamp)
 		{
 			/*
-			 * Current timestamp is in same bucket as the the last limit that
+			 * Current timestamp is in same bucket as the last limit that
 			 * was applied. Reuse.
 			 */
 			xlimit = threshold_xid;