Change xlog to WAL in some error messages

src/backend/access/transam/twophase.c

@@ -1259,13 +1259,13 @@ XlogReadTwoPhaseData(XLogRecPtr lsn, char **buf, int *len)
 		ereport(ERROR,
 				(errcode(ERRCODE_OUT_OF_MEMORY),
 				 errmsg("out of memory"),
-		   errdetail("Failed while allocating an XLog reading processor.")));
+		   errdetail("Failed while allocating a WAL reading processor.")));
 
 	record = XLogReadRecord(xlogreader, lsn, &errormsg);
 	if (record == NULL)
 		ereport(ERROR,
 				(errcode_for_file_access(),
-				 errmsg("could not read two-phase state from xlog at %X/%X",
+				 errmsg("could not read two-phase state from WAL at %X/%X",
 						(uint32) (lsn >> 32),
 						(uint32) lsn)));
 
@@ -1273,7 +1273,7 @@ XlogReadTwoPhaseData(XLogRecPtr lsn, char **buf, int *len)
 		(XLogRecGetInfo(xlogreader) & XLOG_XACT_OPMASK) != XLOG_XACT_PREPARE)
 		ereport(ERROR,
 				(errcode_for_file_access(),
-				 errmsg("expected two-phase state data is not present in xlog at %X/%X",
+				 errmsg("expected two-phase state data is not present in WAL at %X/%X",
 						(uint32) (lsn >> 32),
 						(uint32) lsn)));
 

src/backend/access/transam/xlog.c

@@ -6315,7 +6315,7 @@ StartupXLOG(void)
 		ereport(ERROR,
 				(errcode(ERRCODE_OUT_OF_MEMORY),
 				 errmsg("out of memory"),
-		   errdetail("Failed while allocating an XLog reading processor.")));
+		   errdetail("Failed while allocating a WAL reading processor.")));
 	xlogreader->system_identifier = ControlFile->system_identifier;
 
 	/*
@@ -11246,8 +11246,8 @@ rm_redo_error_callback(void *arg)
 	initStringInfo(&buf);
 	xlog_outdesc(&buf, record);
 
-	/* translator: %s is an XLog record description */
-	errcontext("xlog redo at %X/%X for %s",
+	/* translator: %s is a WAL record description */
+	errcontext("WAL redo at %X/%X for %s",
 			   (uint32) (record->ReadRecPtr >> 32),
 			   (uint32) record->ReadRecPtr,
 			   buf.data);

src/backend/utils/misc/guc.c

@@ -1678,7 +1678,7 @@ static struct config_int ConfigureNamesInt[] =
 {
 	{
 		{"archive_timeout", PGC_SIGHUP, WAL_ARCHIVING,
-			gettext_noop("Forces a switch to the next xlog file if a "
+			gettext_noop("Forces a switch to the next WAL file if a "
 						 "new file has not been started within N seconds."),
 			NULL,
 			GUC_UNIT_S