Remove the placeholder LWLockId in place of the removed FreeSpaceLock.

As pointed out by ITAGAKI Takahiro, we split SInvalLock into two in 8.4,
so to keep the numbers of the rest of the locks unchanged from 8.3, we
don't need a placeholder.

src/include/storage/lwlock.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/lwlock.h,v 1.41 2009/01/01 17:24:01 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/storage/lwlock.h,v 1.42 2009/03/03 08:11:24 heikki Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -36,9 +36,9 @@
  * The extra value MaxDynamicLWLock is there to keep the compiler from
  * deciding that the enum can be represented as char or short ...
  *
- * If you remove a lock, please replace it with a placeholder like was done
- * for FreeSpaceMapLock. This retains the lock numbering, which is helpful for
- * DTrace and other external debugging scripts.
+ * If you remove a lock, please replace it with a placeholder. This retains
+ * the lock numbering, which is helpful for DTrace and other external
+ * debugging scripts.
  */
 typedef enum LWLockId
 {
@@ -49,7 +49,6 @@ typedef enum LWLockId
 	ProcArrayLock,
 	SInvalReadLock,
 	SInvalWriteLock,
-	UnusedLock1,				/* FreeSpaceMapLock used to be here */
 	WALInsertLock,
 	WALWriteLock,
 	ControlFileLock,