[patch] Increase the bar of printing `handling possible serial event'

[Yao Qi <yao@codesourcery.com>]

Hi,
When I debug gdbserver by setting debug_thread to 1, I get many lines
of `handling possible serial event' in log, which dose not carry any
useful information for debugging purpose.

This patch is to increase the threshold of printing this sentence.  Or we
may remove this print completely, because I can't figure out a case
some one wants to read many lines of `handling possible serial event'
in log.

-- 
Yao (齐尧) 

	* server.c (handle_serial_event): Increase the bar to print
	debug message.

diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index 4612457..845ae3a 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -3217,7 +3217,7 @@ process_serial_event (void)
 int
 handle_serial_event (int err, gdb_client_data client_data)
 {
-  if (debug_threads)
+  if (debug_threads > 3)
     fprintf (stderr, "handling possible serial event\n");
 
   /* Really handle it.  */