Send X11 keycode to xorgxrdp

For key events, send the X11 keycode (currently based on evdev) to xorgxrdp
rather than the Unicode character mapping for the key. This gives us a
single source of truth for RDP scancode to X11 keycode mapping.

At present xorgxrdp doesn't use the Unicode character, so no change is
required at that end for this commit.

xup/xup.c

@@ -26,6 +26,7 @@
 #include "log.h"
 #include "trans.h"
 #include "string_calls.h"
+#include "scancode.h"
 
 static int
 send_server_monitor_update(struct mod *v, struct stream *s,
@@ -306,6 +307,11 @@ lib_mod_event(struct mod *mod, int msg, tbus param1, tbus param2,
                 mod->shift_state = msg == 15;
             }
         }
+
+        /* xup doesn't need the Unicode character mapping in param1. Send
+         * the X11 scancode instead, so xorgxrdp doesn't have to do this
+         * work again */
+        param1 = scancode_to_keycode(param3);
     }
 
     init_stream(s, 8192);