It seems that the user-specific data/config directory of midnight commander 4.8.x is under $HOME/.local/share/mc and $HOME/.config/mc. However the previous version(4.7.x) is looking for $HOME/.mc. You can verify that by typing

mc -F

Personally I don't like this change since I prefer to a single directory for the convenience of storage and backup of my config files. Your skin setting probably take no effect after upgrading to 4.8.x. Place your skin files to $HOME/.local/share/mc/skins and modify $HOME/.config/mc/ini