Hi, I closed this issue years ago because actually 0ad doesn't use the squish library which is in the 0ad source.
It's a problem strictly related to the nvidia-texture-tools package. Actually 0ad source could also be repackaged to remove squish and nvtt directory, which are not used. Since there is already bug #838056 for nvidia-texture-tools there is nothing to be done here and this one could actually be closed. But I'll leave that up to you. Related: https://github.com/castano/nvidia-texture-tools/pull/244
