Add some const decorations to array constants

Author: Mark G <markg735@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CAEeOP_YFVeFjq4zDZLDQbLSRFxBiTpwBQHxCNgGd%2Bp5VztTXyQ%40mail.gmail.com

src/backend/access/transam/xlog.c

@@ -769,7 +769,7 @@ typedef enum
 } XLogSource;
 
 /* human-readable names for XLogSources, for debugging output */
-static const char *xlogSourceNames[] = {"any", "archive", "pg_wal", "stream"};
+static const char *const xlogSourceNames[] = {"any", "archive", "pg_wal", "stream"};
 
 /*
  * openLogFile is -1 or a kernel FD for an open log file segment.

src/backend/replication/basebackup.c

@@ -131,7 +131,7 @@ static bool noverify_checksums = false;
  * Note: this list should be kept in sync with the filter lists in pg_rewind's
  * filemap.c.
  */
-static const char *excludeDirContents[] =
+static const char *const excludeDirContents[] =
 {
 	/*
 	 * Skip temporary statistics files. PG_STAT_TMP_DIR must be skipped even
@@ -172,7 +172,7 @@ static const char *excludeDirContents[] =
 /*
  * List of files excluded from backups.
  */
-static const char *excludeFiles[] =
+static const char *const excludeFiles[] =
 {
 	/* Skip auto conf temporary file. */
 	PG_AUTOCONF_FILENAME ".tmp",