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

diff --git a/windows/input.c b/windows/input.c
index 0828204..f1660f5 100644
--- a/windows/input.c
+++ b/windows/input.c
@@ -17,6 +17,7 @@
 #include "winuser.h"
 #include "wine/winbase16.h"
 #include "wine/winuser16.h"
+#include "wine/keyboard16.h"
 #include "win.h"
 #include "gdi.h"
 #include "heap.h"