Make the font ptr const in nk_style_push_font

nuklear.h

@@ -2064,7 +2064,7 @@ NK_API int nk_style_set_cursor(struct nk_context*, enum nk_style_cursor);
 NK_API void nk_style_show_cursor(struct nk_context*);
 NK_API void nk_style_hide_cursor(struct nk_context*);
 
-NK_API int nk_style_push_font(struct nk_context*, struct nk_user_font*);
+NK_API int nk_style_push_font(struct nk_context*, const struct nk_user_font*);
 NK_API int nk_style_push_float(struct nk_context*, float*, float);
 NK_API int nk_style_push_vec2(struct nk_context*, struct nk_vec2*, struct nk_vec2);
 NK_API int nk_style_push_style_item(struct nk_context*, struct nk_style_item*, struct nk_style_item);
@@ -16839,7 +16839,7 @@ nk_style_set_font(struct nk_context *ctx, const struct nk_user_font *font)
 }
 
 NK_API int
-nk_style_push_font(struct nk_context *ctx, struct nk_user_font *font)
+nk_style_push_font(struct nk_context *ctx, const struct nk_user_font *font)
 {
     struct nk_config_stack_user_font *font_stack;
     struct nk_config_stack_user_font_element *element;