Declare __mp_lock_spinout in a single place

Using a single decl helps the compiler catch type mismatches.  In this
case it would have saved claudio some time while trying a wip diff.
ok claudio@ miod@

Author: jcourreges

sys/arch/amd64/amd64/pmap.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.178 2024/11/02 07:58:58 mpi Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.179 2025/06/18 15:05:53 jca Exp $	*/
 /*	$NetBSD: pmap.c,v 1.3 2003/05/08 18:13:13 thorpej Exp $	*/
 
 /*
@@ -3185,7 +3185,6 @@ pmap_steal_memory(vsize_t size, vaddr_t *start, vaddr_t *end)
  */
 #ifdef MP_LOCKDEBUG
 #include <ddb/db_output.h>
-extern int __mp_lock_spinout;
 #endif
 
 volatile long tlb_shoot_wait __attribute__((section(".kudata")));

sys/arch/amd64/amd64/vmm_machdep.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: vmm_machdep.c,v 1.57 2025/06/03 19:15:29 sf Exp $ */
+/* $OpenBSD: vmm_machdep.c,v 1.58 2025/06/18 15:05:53 jca Exp $ */
 /*
  * Copyright (c) 2014 Mike Larkin <[email protected]>
  *
@@ -48,7 +48,6 @@
 
 #ifdef MP_LOCKDEBUG
 #include <ddb/db_output.h>
-extern int __mp_lock_spinout;
 #endif /* MP_LOCKDEBUG */
 
 void *l1tf_flush_region;

sys/arch/hppa/hppa/lock_machdep.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: lock_machdep.c,v 1.15 2024/07/03 01:36:50 jsg Exp $	*/
+/*	$OpenBSD: lock_machdep.c,v 1.16 2025/06/18 15:05:53 jca Exp $	*/
 
 /*
  * Copyright (c) 2007 Artur Grabowski <[email protected]>
@@ -70,9 +70,6 @@ ___mp_lock_init(struct __mp_lock *lock)
 #ifndef DDB
 #error "MP_LOCKDEBUG requires DDB"
 #endif
-
-/* CPU-dependent timing, this needs to be settable from ddb. */
-extern int __mp_lock_spinout;
 #endif
 
 static __inline void

sys/arch/m88k/m88k/mutex.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.c,v 1.1 2020/05/26 11:55:10 aoyama Exp $	*/
+/*	$OpenBSD: mutex.c,v 1.2 2025/06/18 15:05:53 jca Exp $	*/
 
 /*
  * Copyright (c) 2020 Miodrag Vallat
@@ -28,10 +28,6 @@
 
 #include <ddb/db_output.h>
 
-#ifdef MP_LOCKDEBUG
-extern int __mp_lock_spinout;	/* kern_lock.c */
-#endif /* MP_LOCKDEBUG */
-
 static inline int
 atomic_swap(volatile int *lockptr, int new)
 {

sys/arch/powerpc/powerpc/lock_machdep.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: lock_machdep.c,v 1.12 2024/04/03 19:30:59 gkoehler Exp $	*/
+/*	$OpenBSD: lock_machdep.c,v 1.13 2025/06/18 15:05:53 jca Exp $	*/
 
 /*
  * Copyright (c) 2021 George Koehler <[email protected]>
@@ -42,9 +42,6 @@
 #ifndef DDB
 #error "MP_LOCKDEBUG requires DDB"
 #endif
-
-/* CPU-dependent timing, needs this to be settable from ddb. */
-extern int __mp_lock_spinout;
 #endif
 
 static __inline void

sys/sys/systm.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: systm.h,v 1.174 2025/06/16 20:21:33 kettenis Exp $	*/
+/*	$OpenBSD: systm.h,v 1.175 2025/06/18 15:05:53 jca Exp $	*/
 /*	$NetBSD: systm.h,v 1.50 1996/06/09 04:55:09 briggs Exp $	*/
 
 /*-
@@ -107,6 +107,10 @@ extern struct vnode *swapdev_vp;/* vnode equivalent to above */
 
 extern int nowake;		/* dead wakeup(9) channel */
 
+#ifdef MP_LOCKDEBUG
+extern int __mp_lock_spinout;
+#endif
+
 struct proc;
 struct process;
 #define curproc curcpu()->ci_curproc