This is much cleaner than sharing python-dir.bbclass between python 2
and 3 classes, and doing confusing overrides in them.
(From OE-Core rev: 3891fcec863602a0ae6d0f3d305ea50a79a205d9)
Signed-off-by: Alexander Kanavin <alexander.kanavin@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>