When given an absolute path for e.g. CMAKE_INSTALL_LIBDIR, cmake does NOT prepend CMAKE_INSTALL_PREFIX, that is only done for relative paths (see the CMake manual)

However path wrangling in draco_install.cmake always unconditionally prepends the prefix, leading to broken installs e.g. on NixOS. Nix always passes absolute paths to cmake for the specific install directories, as they may have different prefixes in order to split large packages into smaller ones (such as having a separate package for documentation or data files).