Fix inconsistencies and typos in the tree, take 11

This fixes various typos in docs and comments, and removes some orphaned
definitions.

Author: Alexander Lakhin
Discussion: https://postgr.es/m/5da8e325-c665-da95-21e0-c8a99ea61fbf@gmail.com

src/backend/access/heap/tuptoaster.c

@@ -44,8 +44,6 @@
 #include "utils/typcache.h"
 
 
-#undef TOAST_DEBUG
-
 /*
  *	The information at the start of the compressed toast data.
  */

src/backend/access/transam/varsup.c

@@ -488,7 +488,7 @@ ForceTransactionIdLimitUpdate(void)
 	if (!TransactionIdIsValid(xidVacLimit))
 		return true;			/* this shouldn't happen anymore either */
 	if (TransactionIdFollowsOrEquals(nextXid, xidVacLimit))
-		return true;			/* past VacLimit, don't delay updating */
+		return true;			/* past xidVacLimit, don't delay updating */
 	if (!SearchSysCacheExists1(DATABASEOID, ObjectIdGetDatum(oldestXidDB)))
 		return true;			/* could happen, per comments above */
 	return false;

src/backend/access/transam/xact.c

@@ -92,8 +92,8 @@ int			synchronous_commit = SYNCHRONOUS_COMMIT_ON;
  * in the user backend, so we need some additional bookkeeping.
  *
  * XactTopFullTransactionId stores the XID of our toplevel transaction, which
- * will be the same as TopTransactionState.fullTransactionId in an ordinary
- * backend; but in a parallel backend, which does not have the entire
+ * will be the same as TopTransactionStateData.fullTransactionId in an
+ * ordinary backend; but in a parallel backend, which does not have the entire
  * transaction state, it will instead be copied from the backend that started
  * the parallel operation.
  *

src/backend/access/transam/xlog.c

@@ -626,7 +626,7 @@ typedef struct XLogCtlData
 
 	/*
 	 * These values do not change after startup, although the pointed-to pages
-	 * and xlblocks values certainly do.  xlblock values are protected by
+	 * and xlblocks values certainly do.  xlblocks values are protected by
 	 * WALBufMappingLock.
 	 */
 	char	   *pages;			/* buffers for unwritten XLOG pages */
@@ -743,7 +743,7 @@ static ControlFileData *ControlFile = NULL;
  */
 #define UsableBytesInPage (XLOG_BLCKSZ - SizeOfXLogShortPHD)
 
-/* Convert min_wal_size_mb and max wal_size_mb to equivalent segment count */
+/* Convert min_wal_size_mb and max_wal_size_mb to equivalent segment count */
 #define ConvertToXSegs(x, segsize)	\
 	(x / ((segsize) / (1024 * 1024)))
 
@@ -903,7 +903,7 @@ static XLogRecord *ReadRecord(XLogReaderState *xlogreader, XLogRecPtr RecPtr,
 							  int emode, bool fetching_ckpt);
 static void CheckRecoveryConsistency(void);
 static XLogRecord *ReadCheckpointRecord(XLogReaderState *xlogreader,
-										XLogRecPtr RecPtr, int whichChkpti, bool report);
+										XLogRecPtr RecPtr, int whichChkpt, bool report);
 static bool rescanLatestTimeLine(void);
 static void WriteControlFile(void);
 static void ReadControlFile(void);
@@ -3049,9 +3049,9 @@ XLogBackgroundFlush(void)
 	else if (TimestampDifferenceExceeds(lastflush, now, WalWriterDelay))
 	{
 		/*
-		 * Flush the writes at least every WalWriteDelay ms. This is important
-		 * to bound the amount of time it takes for an asynchronous commit to
-		 * hit disk.
+		 * Flush the writes at least every WalWriterDelay ms. This is
+		 * important to bound the amount of time it takes for an asynchronous
+		 * commit to hit disk.
 		 */
 		WriteRqst.Flush = WriteRqst.Write;
 		lastflush = now;
@@ -8442,7 +8442,7 @@ LogCheckpointEnd(bool restartpoint)
  * Update the estimate of distance between checkpoints.
  *
  * The estimate is used to calculate the number of WAL segments to keep
- * preallocated, see XLOGFileSlop().
+ * preallocated, see XLOGfileslop().
  */
 static void
 UpdateCheckPointDistanceEstimate(uint64 nbytes)

src/backend/access/transam/xlogfuncs.c

@@ -267,7 +267,7 @@ pg_stop_backup_v2(PG_FUNCTION_ARGS)
 	values[0] = LSNGetDatum(stoppoint);
 
 	tuplestore_putvalues(tupstore, tupdesc, values, nulls);
-	tuplestore_donestoring(typstore);
+	tuplestore_donestoring(tupstore);
 
 	return (Datum) 0;
 }

src/backend/access/transam/xlogutils.c

@@ -523,7 +523,7 @@ XLogReadBufferExtended(RelFileNode rnode, ForkNumber forknum,
 }
 
 /*
- * Struct actually returned by XLogFakeRelcacheEntry, though the declared
+ * Struct actually returned by CreateFakeRelcacheEntry, though the declared
  * return type is Relation.
  */
 typedef struct