Add missing space in comments.

Author: Junwang Zhao
Discussion: https://postgr.es/m/CAEG8a3++YQ6A-y5-w6KxP8QH6qxDJDk4dEtZw0cLcW9bsQFydg@mail.gmail.com

src/include/storage/lockdefs.h

@@ -36,8 +36,8 @@ typedef int LOCKMODE;
 #define AccessShareLock			1	/* SELECT */
 #define RowShareLock			2	/* SELECT FOR UPDATE/FOR SHARE */
 #define RowExclusiveLock		3	/* INSERT, UPDATE, DELETE */
-#define ShareUpdateExclusiveLock 4	/* VACUUM (non-FULL),ANALYZE, CREATE INDEX
-									 * CONCURRENTLY */
+#define ShareUpdateExclusiveLock 4	/* VACUUM (non-FULL), ANALYZE, CREATE
+									 * INDEX CONCURRENTLY */
 #define ShareLock				5	/* CREATE INDEX (WITHOUT CONCURRENTLY) */
 #define ShareRowExclusiveLock	6	/* like EXCLUSIVE MODE, but allows ROW
 									 * SHARE */