What the error message tells us, this package `libtxc-dxtn-s2tc0:i386` is needed to be installed, but it depends on package `libstdc++6:i386` which should be version 4.1.1 or later, but that cannot be installed (either because 4.1.1 is not available, which is very unlikely, or somehow this package is marked to stick with another version)
same happened with python, python-all, python-all-dev packages