Update code comments for pg_xlog -> pg_wal

Author: Michael Paquier <michael.paquier@gmail.com>

src/bin/pg_basebackup/walmethods.c

@@ -31,7 +31,7 @@
 #define ZLIB_OUT_SIZE 4096
 
 /*-------------------------------------------------------------------------
- * WalDirectoryMethod - write wal to a directory looking like pg_xlog
+ * WalDirectoryMethod - write wal to a directory looking like pg_wal
  *-------------------------------------------------------------------------
  */
 
@@ -375,7 +375,7 @@ FreeWalDirectoryMethod(void)
 
 
 /*-------------------------------------------------------------------------
- * WalTarMethod - write wal to a tar file containing pg_xlog contents
+ * WalTarMethod - write wal to a tar file containing pg_wal contents
  *-------------------------------------------------------------------------
  */
 

src/bin/pg_basebackup/walmethods.h

@@ -80,8 +80,8 @@ struct WalWriteMethod
 
 /*
  * Available WAL methods:
- *	- WalDirectoryMethod - write WAL to regular files in a standard pg_xlog
- *	- TarDirectoryMethod - write WAL to a tarfile corresponding to pg_xlog
+ *	- WalDirectoryMethod - write WAL to regular files in a standard pg_wal
+ *	- TarDirectoryMethod - write WAL to a tarfile corresponding to pg_wal
  *						   (only implements the methods required for pg_basebackup,
  *						   not all those required for pg_receivewal)
  */