config: drop useless length variable in write_pair()
We compute the length of a subset of a string, but then use that length
only to feed a "%.*s" printf placeholder for the same string. We can
just use "%s" to achieve the same thing.
The variable became useless in
cb891a5989 (Use a strbuf for building up
section header and key/value pair strings., 2007-12-14), which swapped
out a write() which _did_ use the length for a strbuf_addf() call.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>