assimp vendors a *lot* of its own libraries, which is generally an
anti-pattern for distros as it leads to duplicate work, both for fixing
any issues and build compute. unfortunately, assimp does not make it
easy to pull in system libraries (there is an open issue for it, but
little progress seems to have been made in a few years), so we patch the
CMake declarations to use our own in the same way that Fedora and Debian
already do.
