Barebox starting from 2019.02 no longer ships flex/bison generated
parser. Add conditional kconfig dependencies, same as we did for kernel
and uboot.
Signed-off-by: Marcin Niestroj <m.niestroj@grinn-global.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
(cherry picked from commit e7d8d9a765)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>