Update menuconfig and Kconfiglib to upstream revision 16539b4f223fa, to
add the commit below.
menuconfig: Prompt for save if a different .config would be saved
Previously, menuconfig.py only prompted for saving the configuration
if .config didn't exist or the user changed symbol values within the
interface.
Also make it prompt for save if Kconfig symbols have been added,
removed, or have had their defaults changed, provided it would make
the saved .config differ from the loaded one.
This usually won't matter for correctness, because loading an
outdated configuration performs an implicit olddefconfig, but it's
less confusing.
Also add a Kconfig.missing_syms attribute that records all
assignments to undefined symbols in the most recently loaded .config
file. This is needed to implement the check for whether the saved
.config would be different.
As an unrelated change, always prompt for saving if a .config has
been loaded from within the menuconfig interface. The intention is
probably often to save the configuration somewhere else, even if it
isn't modified.
Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>