Fix the build to pull from upstream sel4-sys
Remove the dependency for sel4-sys
being on the local filesystem. You can always provide a cargo override in the cargo configuration file (http://doc.crates.io/config.html) for local development.
# An array of paths to local repositories which are to be used as overrides for
# dependencies. For more information see the Specifying Dependencies guide.
paths = ["/path/to/override"]
Additionally, I documented the python build requirements that sel4-sys has.