python: fix build error for missing library_path in setup.py

Patch obtained from gentoo package.

https://bugs.gentoo.org/show_bug.cgi?id=477110
https://bugs.gentoo.org/show_bug.cgi?id=490584

Signed-off-by: Thomas Haller <thaller@redhat.com>
doc: fix typo in documentation

Also fix typo in source code comment.

Signed-off-by: Thomas Haller <thaller@redhat.com>