base.bbclass: Work even when there's no PNBLACKLIST entries
It turns out that the result of getVarFlags is not a list, it's
a dict. So "getVarFlags(...) or []" does not reliably produce
something with a .items. This escaped detection because our
local build environment never ends up running builds without
PNBLACKLIST entries.
Signed-off-by: Peter Seebach <peter.seebach@windriver.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
