Attempt to fix a bug with inputs on mobile

Not really sure what the problem is, but without this change the UI
doesn't behave well on android, and some UI inputs are captured by goxel.

src/gui.cpp

@@ -1987,7 +1987,12 @@ bool gui_icons_grid(int nb, const gui_icon_info_t *icons, int *current)
 
 bool gui_want_capture_mouse(void)
 {
-    return gui && gui->want_capture_mouse;
+    /* Note: we check both gui->want_capture_mouse and
+     * io.WantCaptureMouse otherwise there seems to be some subtle input
+     * errors on mobile */
+    gui_init();
+    ImGuiIO& io = ImGui::GetIO();
+    return (gui && gui->want_capture_mouse) || io.WantCaptureMouse;
 }
 
 bool gui_context_menu_begin(const char *label)