Simplify key round-tripping to IBUS

Only send to IBUS after full xkb processing. This is needed as otherwise
modifier state tracking does not work reliably. If you use alt+tab to
switch away from the window, the window never receives the release event
for the alt modifier.

The downside is that now if the uer has both XCompose and ibus active,
the who knows what will happen.

glfw/ibus_glfw.h

@@ -43,6 +43,8 @@ typedef struct {
     unsigned int glfw_modifiers;
     int action;
     GLFWid window_id;
+    int glfw_keycode;
+    char text[64];
 } KeyEvent;
 
 void glfw_connect_to_ibus(_GLFWIBUSData *ibus);