python - be: Rely on relative paths.

Log Message:
-----------
Rely on relative paths. setup already relies on relative paths, so just finish
the job everywhere else. The removed code caused setup.cache to not be found if
setup were to be invoked outside of setup's directory.

Modified Files:
--------------
be/lib:
ldistutils.py (r1.9 -> r1.10)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/lib/ldistutils.py.diff?r1=1.9&r2=1.10)
be:
setup.py (r1.16 -> r1.17)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/setup.py.diff?r1=1.16&r2=1.17)