misc: remove resource tool image bitmap block

This was giving me issues on Win10, right click context menus were failing to get text.

src/gui/util.cpp

@@ -245,13 +245,7 @@ void set_menu_item_image(wxMenuItem* item, const String& resource) {
     if (item->GetKind() == wxITEM_CHECK) return; // check items can't have icons
   #endif
   Image bitmap = load_resource_tool_image(resource);
-  #if defined(__WXMSW__)
-    Image disabled_bitmap = generate_disabled_image(bitmap);
-    item->SetBitmaps(bitmap, bitmap);
-    item->SetDisabledBitmap(disabled_bitmap);
-  #else
-    item->SetBitmap(bitmap);
-  #endif
+  item->SetBitmap(bitmap);
 }
 
 wxMenuItem* make_menu_item(wxMenu* menu, int id, const char* resource, const String& text, const String& help, wxItemKind kind, wxMenu* submenu) {

src/gui/value/choice.cpp

@@ -134,7 +134,7 @@ void DropDownChoiceListBase::drawIcon(DC& dc, int x, int y, size_t item, bool se
     image_id = getChoice(item)->first_id;
   }
   // draw image
-  if (image_id < style().thumbnails.size()) {
+  if ((unsigned int) image_id < style().thumbnails.size()) {
     auto const& thumbnail = style().thumbnails[image_id];
     if (thumbnail.status == THUMB_OK)
     dc.DrawBitmap(thumbnail.bitmap, x, y);