data_smart/utils: Add 'd' to the context used for better_eval in python expansion

data_smart/utils: Add 'd' to the context used for better_eval in python expansion

If a line like:

foo=${@' '.join([d.getVar('D', True) + x for x in (' '.join([d.getVar('FILES_bash-' + p, True) or '' for p in ['lib', 'dev', 'staticdev', 'doc', 'locale', 'ptest']])).split()])}

is added to a function like do_install, it fails with Exception name 'd'
is not defined. This is due to a change of behaviour in python 3 compared
to python 2. Generator expressions, dict comprehensions  and set comprehensions
are executed in a new scope but list comprehensions in python 2.x are not. In
python 3 they all use a new scope.

To allow these kinds of expressions to work, the easiest approach is
to add 'd' to the global context. To do this, an extra optional parameter
is added to better_eval and we use that to add 'd'.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>