Hmm, so evidently _check_lock and _clear_lock take an argument of type

int not unsigned int.  Third try to get grebe building without warnings...

src/include/storage/s_lock.h

@@ -66,7 +66,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- *	  $PostgreSQL: pgsql/src/include/storage/s_lock.h,v 1.161 2007/07/16 04:57:57 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/include/storage/s_lock.h,v 1.162 2007/07/16 14:02:22 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -752,7 +752,7 @@ typedef abilock_t slock_t;
 
 #include <sys/atomic_op.h>
 
-typedef unsigned int slock_t;
+typedef int slock_t;
 
 #define TAS(lock)			_check_lock((slock_t *) (lock), 0, 1)
 #define S_UNLOCK(lock)		_clear_lock((slock_t *) (lock), 0)