write_file() either returns 0 or dies, so there is no point in checking
its return value. The callers of the wrappers write_state_text(),
write_state_count() and write_state_bool() consequently already ignore
their return values. Stop pretending we care and make them void.
Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>