The patch 4a1a58a3 build, imagebuilder: Do not require libncurses-dev
was supposed to remove libncurses as a requirement for the ImageBuilder.
However as the IB=1 is only exported during building, not for checking
requirements, it did never actually work.
This commit export IB=1 to the requirement check.
Signed-off-by: Paul Spooren <mail@aparcar.org>