Optimized debugging API to reduce code size.

diff --git a/msdos/int41.c b/msdos/int41.c
index 76f3554..905218a 100644
--- a/msdos/int41.c
+++ b/msdos/int41.c
@@ -6,6 +6,9 @@
 
 #include <stdio.h>
 #include "miscemu.h"
+#include "debugtools.h"
+
+DEFAULT_DEBUG_CHANNEL(int);
 
 /***********************************************************************
  *           INT_Int41Handler