add scaffolding in imperative shell to help update canvas width and height

ffi/glfw-input.c

@@ -20,6 +20,7 @@ int KEY_I = GLFW_KEY_I;
 int KEY_L = GLFW_KEY_L;
 int KEY_O = GLFW_KEY_O;
 int KEY_A = GLFW_KEY_A;
+int KEY_W = GLFW_KEY_W;
 
 int KEY_ENTER = GLFW_KEY_ENTER;
 int KEY_SPACE = GLFW_KEY_SPACE;