pylibfdt: fix swig build in install

A 'pip install' is silently broken unless the tree is dirty and contains
pylibfdt/libfdt.py. The problem is a known issue[1] with SWIG and
setuptools where the 'build_py' stage needing module.py runs before
the 'build_ext' stage which generates it. The work-around is to override
'build_py' to run 'build_ext' first.

[1] https://stackoverflow.com/questions/50239473/building-a-module-with-setuptools-and-swig

Signed-off-by: Rob Herring <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: David Gibson <[email protected]>
2 files changed