Allocate a few extra LWLocks for possible use by add-on modules.

Per request from Marc Munro.

src/backend/storage/lmgr/lwlock.c

@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/lmgr/lwlock.c,v 1.30 2005/09/16 00:30:05 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/lmgr/lwlock.c,v 1.31 2005/10/07 20:11:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -140,7 +140,8 @@ NumLWLocks(void)
 	 */
 	numLocks += 2 * NUM_SLRU_BUFFERS;
 
-	/* Perhaps create a few more for use by user-defined modules? */
+	/* Leave a few extra for use by user-defined modules. */
+	numLocks += NUM_USER_DEFINED_LWLOCKS;
 
 	return numLocks;
 }

src/include/pg_config_manual.h

@@ -6,7 +6,7 @@
  * for developers.	If you edit any of these, be sure to do a *full*
  * rebuild (and an initdb if noted).
  *
- * $PostgreSQL: pgsql/src/include/pg_config_manual.h,v 1.17 2005/10/03 22:55:56 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/pg_config_manual.h,v 1.18 2005/10/07 20:11:03 tgl Exp $
  *------------------------------------------------------------------------
  */
 
@@ -74,6 +74,11 @@
  */
 #define INDEX_MAX_KEYS		32
 
+/*
+ * Number of spare LWLocks to allocate for user-defined add-on code.
+ */
+#define NUM_USER_DEFINED_LWLOCKS	4
+
 /*
  * Define this to make libpgtcl's "pg_result -assign" command process
  * C-style backslash sequences in returned tuple data and convert