distutils3: do out of tree builds

distutils3: do out of tree builds

Pass --build-base so the build tree is a location we specify, which we
can ensure is empty when building.

This means we can stub out do_configure entirely and use cleandirs
instead.

When installing we need to tell it to do a build so that we can pass
--build-base, so also pass --skip-build to avoid the potential rebuild.

Signed-off-by: Ross Burton <ross.burton@intel.com>