Fix a build failure on OpenBSD 4.x and MirBSD.

* sysdep.c (list_system_processes): Make it a stub on all BSD_SYSTEM
hosts, except for DARWIN_OS and FreeBSD where it's been tested.

Fixes: debbugs:13881

src/ChangeLog

 2013-03-05  Paul Eggert  <eggert@cs.ucla.edu>
 	Fix a build failure on OpenBSD 4.x and MirBSD (Bug#13881).
-	* sysdep.c (list_system_processes) [__OpenBSD__ || __MirBSD__]:
+	* sysdep.c (list_system_processes)
+	[BSD_SYSTEM && !DARWIN_OS && !__FreeBSD__]:
 	Make it a stub in this case; otherwise the build might fail,
-	and even if the build worked the function would just return nil anyway.
+	and this code hasn't been tested on such hosts anyway.
 	Problem reported by Nelson H. F. Beebe in
 	<http://lists.gnu.org/archive/html/emacs-devel/2013-03/msg00021.html>
 	and analyzed by Jérémie Courrèges-Anglas in

src/sysdep.c

@@ -2647,12 +2647,12 @@ list_system_processes (void)
   return proclist;
 }
 
-#elif defined BSD_SYSTEM && !defined __OpenBSD__ && !defined __MirBSD__
+#elif defined DARWIN_OS || defined __FreeBSD__
 
 Lisp_Object
 list_system_processes (void)
 {
-#if defined DARWIN_OS || defined __NetBSD__
+#ifdef DARWIN_OS
   int mib[] = {CTL_KERN, KERN_PROC, KERN_PROC_ALL};
 #else
   int mib[] = {CTL_KERN, KERN_PROC, KERN_PROC_PROC};
@@ -2678,7 +2678,7 @@ list_system_processes (void)
   len /= sizeof (struct kinfo_proc);
   for (i = 0; i < len; i++)
     {
-#if defined DARWIN_OS || defined __NetBSD__
+#ifdef DARWIN_OS
       proclist = Fcons (make_fixnum_or_float (procs[i].kp_proc.p_pid), proclist);
 #else
       proclist = Fcons (make_fixnum_or_float (procs[i].ki_pid), proclist);