check-attr: there are only two possible line terminations

The program by default reads LF terminated lines, with an option to
use NUL terminated records.  Instead of pretending that there can be
other useful values for line_termination, use a boolean variable,
nul_term_line, to tell if NUL terminated records are used, and
switch between strbuf_getline_{lf,nul} based on it.

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

builtin/check-attr.c

@@ -73,12 +73,13 @@ static void check_attr_stdin_paths(const char *prefix, int cnt,
 	struct git_attr_check *check)
 {
 	struct strbuf buf, nbuf;
-	int line_termination = nul_term_line ? 0 : '\n';
+	strbuf_getline_fn getline_fn;
 
+	getline_fn = nul_term_line ? strbuf_getline_nul : strbuf_getline_lf;
 	strbuf_init(&buf, 0);
 	strbuf_init(&nbuf, 0);
-	while (strbuf_getline(&buf, stdin, line_termination) != EOF) {
-		if (line_termination && buf.buf[0] == '"') {
+	while (getline_fn(&buf, stdin) != EOF) {
+		if (!nul_term_line && buf.buf[0] == '"') {
 			strbuf_reset(&nbuf);
 			if (unquote_c_style(&nbuf, buf.buf, NULL))
 				die("line is badly quoted");