Optimized away more includes, readded some #includes for necessary
prototypes.

diff --git a/msdos/dosconf.c b/msdos/dosconf.c
index dd447ac..97ddb56 100644
--- a/msdos/dosconf.c
+++ b/msdos/dosconf.c
@@ -10,7 +10,7 @@
 #include <string.h>
 #include <stdlib.h>
 #include <ctype.h>
-#include "windows.h"
+#include "winbase.h"
 #include "msdos.h"
 #include "debug.h"
 #include "options.h"