The previous code assumes that bitbake/ directory is under the core layer.
This is the case for Yocto project. But users might clone oe-core and bitbake
separately. So we use bb.__file__ to locate the bitbake directory to make sure
it's copied into the extensible SDK.
(From OE-Core rev: 1be1db87343a48e9c25297245a2749d9df25d23c)
Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>