file_write_dep() is called only from conf_write_autoconf().
Move it from util.c to confdata.c to make it static.
Also, rename it to conf_write_dep() since it should belong to
the group of conf_write* functions.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Christian Lamparter <chunkeey@gmail.com>