Commit cb67ab2cd2 ("kconfig: do not write choice values when their
dependency becomes n") fixed a problem where "# CONFIG_... is not set"
for choice values are wrongly written into the .config file when they
are once visible, then become invisible later.
Add a test for this naive case.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Ulf Magnusson <ulfalizer@gmail.com>
