ident.c: read /etc/mailname with strbuf_getline()

Just in case /etc/mailname file was edited with a DOS editor,
read it with strbuf_getline() so that a stray CR is not included
as the last character of the mail hostname.

We _might_ want to more aggressively discard whitespace characters
around the line with strbuf_trim(), but that is a bit outside the
scope of this series.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

ident.c

@@ -76,7 +76,7 @@ static int add_mailname_host(struct strbuf *buf)
 				strerror(errno));
 		return -1;
 	}
-	if (strbuf_getline_lf(&mailnamebuf, mailname) == EOF) {
+	if (strbuf_getline(&mailnamebuf, mailname) == EOF) {
 		if (ferror(mailname))
 			warning("cannot read /etc/mailname: %s",
 				strerror(errno));