FYI: add missing debug_linux_nat

[Tom Tromey <tromey@redhat.com>]

I'm checking this in.

I saw a strange message today:

LND: Sending signal 11 to process 13765

This is caused by a missing test of debug_linux_nat.  Thanks to Pedro
for pointing out the linux-nat.c debugging print convention.

Tom

2010-03-17  Tom Tromey  <tromey@redhat.com>

	* linux-nat.c (linux_nat_detach): Check debug_linux_nat.

Index: linux-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/linux-nat.c,v
retrieving revision 1.164
diff -u -r1.164 linux-nat.c
--- linux-nat.c	24 Feb 2010 17:01:57 -0000	1.164
+++ linux-nat.c	17 Mar 2010 16:14:01 -0000
@@ -1783,10 +1783,11 @@
 	 pass it along with PTRACE_DETACH.  */
       args = alloca (8);
       sprintf (args, "%d", (int) WSTOPSIG (status));
-      fprintf_unfiltered (gdb_stdlog,
-			  "LND: Sending signal %s to %s\n",
-			  args,
- 			  target_pid_to_str (main_lwp->ptid));
+      if (debug_linux_nat)
+	fprintf_unfiltered (gdb_stdlog,
+			    "LND: Sending signal %s to %s\n",
+			    args,
+			    target_pid_to_str (main_lwp->ptid));
     }
 
   delete_lwp (main_lwp->ptid);