Fix many typos and inconsistencies

Author: Alexander Lakhin
Discussion: https://postgr.es/m/af27d1b3-a128-9d62-46e0-88f424397f44@gmail.com

src/backend/access/brin/brin_tuple.c

@@ -1,5 +1,5 @@
 /*
- * brin_tuples.c
+ * brin_tuple.c
  *		Method implementations for tuples in BRIN indexes.
  *
  * Intended usage is that code outside this file only deals with
@@ -207,7 +207,7 @@ brin_form_tuple(BrinDesc *brdesc, BlockNumber blkno, BrinMemTuple *tuple,
 		/*
 		 * Note that we reverse the sense of null bits in this module: we
 		 * store a 1 for a null attribute rather than a 0.  So we must reverse
-		 * the sense of the att_isnull test in br_deconstruct_tuple as well.
+		 * the sense of the att_isnull test in brin_deconstruct_tuple as well.
 		 */
 		bitP = ((bits8 *) ((char *) rettuple + SizeOfBrinTuple)) - 1;
 		bitmask = HIGHBIT;

src/backend/access/nbtree/nbtree.c

@@ -621,8 +621,8 @@ btparallelrescan(IndexScanDesc scan)
 
 /*
  * _bt_parallel_seize() -- Begin the process of advancing the scan to a new
- *		page.  Other scans must wait until we call bt_parallel_release() or
- *		bt_parallel_done().
+ *		page.  Other scans must wait until we call _bt_parallel_release()
+ *		or _bt_parallel_done().
  *
  * The return value is true if we successfully seized the scan and false
  * if we did not.  The latter case occurs if no pages remain for the current

src/backend/access/nbtree/nbtxlog.c

@@ -181,7 +181,7 @@ btree_xlog_insert(bool isleaf, bool ismeta, XLogReaderState *record)
 
 		if (PageAddItem(page, (Item) datapos, datalen, xlrec->offnum,
 						false, false) == InvalidOffsetNumber)
-			elog(PANIC, "btree_insert_redo: failed to add item");
+			elog(PANIC, "btree_xlog_insert: failed to add item");
 
 		PageSetLSN(page, lsn);
 		MarkBufferDirty(buffer);