_PYTHON_PROJECT_BASE and _PYTHON_PROJECT_SRC appear to be set in setup.py from
the source directory and build directory correctly, so this is redundant.
(From OE-Core rev: 983206d4ccab2b27adba2776f73c0c711d3ec98e)
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>