pg_basebackup and pg_rewind: exclude pg_log.

This commit makes pg_rewind to exclude pg_log from performing any
operation, means comparing and copying from current primary to old
primary.

Also, it uses the new upstream style to exclude pg_log in
pg_basebackup.

src/backend/replication/basebackup.c

@@ -162,6 +162,9 @@ static const char *excludeDirContents[] =
 	/* Contents zeroed on startup, see StartupSUBTRANS(). */
 	"pg_subtrans",
 
+	/* Contents unique to each segment instance. */
+	"pg_log",
+
 	/* end of list */
 	NULL
 };
@@ -1202,20 +1205,6 @@ sendDir(char *path, int basepathlen, bool sizeonly, List *tablespaces,
 			continue;			/* don't recurse into pg_xlog */
 		}
 
-		/*
-		 * We can skip pg_log because the segment logs should be unique to
-		 * each segment. However, include pg_log as an empty directory because
-		 * it is required to start the segment.
-		 */
-		if (strcmp(pathbuf, "./pg_log") == 0)
-		{
-			if (!sizeonly)
-				_tarWriteHeader(pathbuf + basepathlen + 1, NULL, &statbuf);
-			size += 512;        /* Size of the header just added */
-
-			continue;
-		}
-
 		/* Skip if client does not want */
 		if (match_exclude_list(pathbuf, exclude))
 			continue;

src/bin/pg_rewind/filemap.c

@@ -76,6 +76,9 @@ static const char *excludeDirContents[] =
 	/* Contents zeroed on startup, see StartupSUBTRANS(). */
 	"pg_subtrans",
 
+	/* Contents unique to each segment instance. */
+	"pg_log",
+
 	/* end of list */
 	NULL
 };