Removed "implicit declaration" warnings.

diff --git a/msdos/ioports.c b/msdos/ioports.c
index beaea7b..49a9f10 100644
--- a/msdos/ioports.c
+++ b/msdos/ioports.c
@@ -20,6 +20,7 @@
 #include "vga.h"
 #include "dosexe.h"
 #include "options.h"
+#include "miscemu.h"
 #include "debug.h"
 #include "miscemu.h"