Reword the string description of native FreeBSD ptids.

The prior format led to confusing messages when threads were created
or added such as "[New process 14757, LWP 100537]".  The new format
reports this as "[New LWP 100434 of process 15652]".

gdb/ChangeLog:

	* fbsd-nat.c (fbsd_pid_to_str): Adjust string format.

gdb/fbsd-nat.c

@@ -303,7 +303,7 @@ fbsd_pid_to_str (struct target_ops *ops, ptid_t ptid)
       static char buf[64];
       int pid = ptid_get_pid (ptid);
 
-      xsnprintf (buf, sizeof buf, "process %d, LWP %d", pid, lwp);
+      xsnprintf (buf, sizeof buf, "LWP %d of process %d", lwp, pid);
       return buf;
     }