Fix missing #include.

--- brandy-1.0.19/src/emulate.c	2005-02-26 19:20:09.000000000 +0000
+++ brandy-1.0.19/src/emulate.c	2025-07-03 16:44:03.822738587 +0100
@@ -51,6 +51,7 @@
 #include "basicdefs.h"
 #include "emulate.h"
 #include "screen.h"
+#include "keyboard.h"
 
 #ifdef TARGET_RISCOS
 #include "kernel.h"