gdbserver: use target_waitstatus::to_string in 'prepare_resume_reply'

Use the to_string method of target_waitstatus in
'prepare_resume_reply' for a more readable log message.

Approved-By: Tom Tromey <tom@tromey.com>
diff --git a/gdbserver/remote-utils.cc b/gdbserver/remote-utils.cc
index f54bbab..722915d 100644
--- a/gdbserver/remote-utils.cc
+++ b/gdbserver/remote-utils.cc
@@ -1053,8 +1053,9 @@
 prepare_resume_reply (char *buf, ptid_t ptid, const target_waitstatus &status)
 {
   client_state &cs = get_client_state ();
-  threads_debug_printf ("Writing resume reply for %s:%d",
-			target_pid_to_str (ptid).c_str (), status.kind ());
+  threads_debug_printf ("Writing resume reply for %s: %s",
+			target_pid_to_str (ptid).c_str (),
+			status.to_string ().c_str ());
 
   switch (status.kind ())
     {